Supplemental Prospectus (Form 424B5)

 Filed Pursuant to Rule 424(b)(5)​

 Registration No. 333-286231​

PROSPECTUS SUPPLEMENT
(To Prospectus Dated April 15, 2025)

Subscription Rights to Purchase an Aggregate of up to 129,033,678 Common Shares of Rare Element Resources Ltd.
Up to 129,033,678 Common Shares of Rare Element Resources Ltd. Issuable Upon the Exercise of Subscription Rights

Rare Element Resources Ltd. (the "Company," "we," "us," or "our") is distributing at no charge to the holders of our common shares, without par value, non-transferable subscription rights to purchase our common shares at a subscription price of $0.24 per share (the "rights offering"). Each holder will receive twenty-five hundredths (or 0.25) of a subscription right for each of our common shares owned by such holder at the close of business on January 30, 2026 (the "record date"). Each whole subscription right will entitle its holder to purchase one of our common shares at the per share subscription price.

The purpose of this rights offering is to raise equity capital for the Company in a manner that allows current equity holders to participate. The net proceeds will be used (i) to support (A) the continuation of the operation of the rare earth processing and separation demonstration plant (the "Demonstration Plant"); (B) the advancement of projects for the as-constructed Demonstration Plant beyond the current neodymium/​praseodymium (Nd/Pr) separation objectives, including applying the technology to the separation of heavy rare earth elements and to third-party feed sources; and (C) the completion of federal and state permitting and licensing for the Bear Lodge rare earth elements project (the "Bear Lodge REE Project"); and (ii) for other general corporate purposes. Please see "Use of Proceeds" for a further explanation of our intended use of proceeds from this rights offering. If we sell all the common shares being offered in this rights offering, we will receive gross proceeds of approximately $30.9 million.

The subscription rights issued pursuant to this rights offering will be granted and exercisable beginning on or about February 6, 2026. The subscription rights will expire and will have no value if they are not exercised prior to 5:00 p.m., Eastern Time, on March 4, 2026, the expected expiration date of this rights offering. We, in our sole discretion, may extend the period for exercising the subscription rights until a date no later than March 6, 2026. We reserve the right to cancel the rights offering at any time before the expiration of the rights offering, for any reason. In the event the rights offering is cancelled, all subscription payments received by the subscription agent will be returned as soon as practicable, without interest or deduction. Computershare Investor Services Inc. will serve as the subscription agent in the rights offering.

You should carefully consider whether to exercise your subscription rights before the expiration of the rights offering and review carefully the contents of this prospectus supplement and the accompanying prospectus prior to exercising such rights. Except in the event that we make a fundamental change to the terms and conditions of the rights offering, all exercises of subscription rights are irrevocable once they are exercised and shall continue to be irrevocable in the event that the rights offering is extended. Our board of directors is making no recommendation regarding your exercise of the subscription rights. Holders who do not participate in the rights offering will continue to own the same number of common shares that they held immediately prior to the completion of the rights offering. Holders who do not subscribe for the greatest number of shares permitted in the rights offering will own a smaller percentage of the total common shares outstanding upon completion of the rights offering if and to the extent other holders fully exercise their basic subscription and oversubscription privileges. Subscription rights that are not exercised by 5:00 p.m., Eastern Time, on the expiration date will expire and have no value. The subscription rights may not be sold or transferred.

Synchron, the majority shareholder of the Company, has advised the Company that it intends to participate in the rights offering, but Synchron has not entered into any written or verbal agreement or other arrangement with the Company to do so, nor has Synchron indicated the circumstances under which

it would participate in the rights offering. In the Company's December 2021 rights offering, approximately 62% of the rights were exercised by Synchron and approximately 38% of the rights were exercised by holders other than Synchron. In the Company's February 2024 rights offering, approximately 82% of the rights were exercised by Synchron and approximately 18% of the rights were exercised by holders other than Synchron. Depending on the extent to which Synchron and holders other than Synchron exercise their subscription rights in this rights offering, Synchron's ownership percentage in our outstanding common shares could be anywhere between approximately 56% and approximately 76% upon completion of the rights offering. See "Risk Factors - Regardless of the extent to which Synchron and holders other than Synchron exercise their subscription rights, Synchron will continue to hold more than 50% of our outstanding common shares after the rights offering . . . ."

Our common shares are quoted on the OTCQB Venture Marketplace under the symbol "REEMF," and the common shares issued pursuant to this rights offering will also be quoted on the OTCQB Venture Marketplace under the same symbol. On February 5, 2026, the last reported sale price of our common shares was $0.79 per share.

If you exercise your basic subscription privilege in full, you may also exercise an oversubscription privilege to purchase additional common shares that remain unsubscribed for at the expiration of the rights offering, subject to availability and pro rata allocation of shares among persons properly exercising the oversubscription privilege. As an illustrative example as to the mechanics of the rights offering, if you own 1,000 of the Company's common shares on the record date, you will receive subscription rights under the basic subscription privilege enabling you to purchase up to 250 common shares at $0.24 per share. If you exercise your basic subscription privilege to purchase all (but not less than all) of the 250 common shares, you could also exercise your oversubscription privilege to purchase additional common shares that remain unsubscribed for as a result of any other shareholders not exercising their basic subscription privilege, subject to the pro rata allocation of shares among rights holders properly exercising their oversubscription privilege.

We will not issue fractional common shares in the rights offering. To the extent that the number of subscription rights that are distributed to you on the record date is not a whole number, the common shares issuable upon exercise of the basic subscription or oversubscription privilege will be rounded down to the nearest whole share for purposes of determining the number of our common shares for which you may subscribe.

Investing in our common shares involves a high degree of risk. We urge you to carefully read the section entitled "Risk Factors" beginning on page S-19 of this prospectus supplement before you decide whether to exercise your rights.

Neither the Securities and Exchange Commission nor any state securities or foreign commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus supplement. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is February 6, 2026.

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus are part of a universal shelf registration statement on Form S-3 (File No. 333-286231) that we filed with the Securities and Exchange Commission (the "SEC"). Under the shelf registration statement, we may sell any combination of senior debt securities, subordinated debt securities, common shares, warrants or units in one or more offerings from time to time. This prospectus supplement describes the specific details regarding the sale of common shares issuable upon exercise of the rights granted in this rights offering, including the price, the aggregate number of common shares that may be purchased by exercise of the rights and the risks of investing in our common shares. This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein include important information about us, the subscription rights, our common shares and other information you should know before exercising your subscription rights.

If the description of the offering varies between this prospectus supplement and the accompanying prospectus, you should rely on the information contained in this prospectus supplement. However, if any statement in one of these documents is inconsistent with a statement in another document having a later date-for example, a document incorporated by reference herein or therein, respectively-the statement in the document having the later date modifies or supersedes the earlier statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement or the accompanying prospectus. Please see "Incorporation of Certain Information by Reference" in the accompanying prospectus for more information.

You should rely only on the information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus, or in any free writing prospectus that will be filed by us or on our behalf with the SEC. We have not authorized anyone to provide you with additional, different or inconsistent information. If anyone provides you with additional, different, or inconsistent information, you should not rely on it. We are not making an offer to sell securities in any jurisdiction in which the offer or sale is not permitted. You should assume that the information in this prospectus supplement is accurate only as of the date on the front cover of this prospectus supplement, the information in the accompanying prospectus is accurate only as of the date set forth therein, and any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, in each case regardless of the time of delivery of this prospectus supplement, the accompanying prospectus, the certificates representing the subscription rights or any exercise of those subscription rights. Our business, financial condition, results of operations, and prospects may have changed since that date.

The distribution of the subscription rights and the common shares issuable upon the exercise thereof in Canada is being made in reliance on the prospectus exemption in section 2.1.2(1) of National Instrument 45-106 - Prospectus Exemptions ("NI 45-106"). This prospectus supplement is not, and under no circumstances is to be construed as, a prospectus, an advertisement, or a public offering of securities in any province or territory of Canada. No prospectus has been filed with any Canadian securities regulatory authority, and no such filing is required in connection with this rights offering as the distribution is being made pursuant to the above-noted exemption from the prospectus requirement under NI 45-106. This prospectus supplement may only be used in connection with the rights offering by persons to whom it may be lawfully delivered in Canada, and only where the rights offering may be lawfully made.

As used in this prospectus supplement, the "Company," "we," "our," and "us" refer to Rare Element Resources Ltd., unless stated otherwise or the context requires otherwise.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and forward-looking information and forward-looking statements within the meaning of applicable Canadian securities laws, with respect to our financial condition, results of operations, business prospects, plans, objectives, goals, strategies, future events, capital expenditures, and exploration and development efforts. Words such as "anticipates," "expects," "intends," "forecasts," "plans," "believes," "seeks," "estimates," "may," "will," and similar expressions (including negative and grammatical variations) tend to identify forward-looking statements.

Although we believe that our plans, intentions and expectations reflected in these forward-looking statements are reasonable, we cannot be certain that these plans, intentions or expectations will be achieved. Actual results, performance or achievements could differ materially from those contemplated, expressed or implied by the forward-looking statements contained in this prospectus supplement.

Any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, intentions, projections, objectives, assumptions or future events or performance (often, but not always, using words or phrases such as "expects" or "does not expect," "is expected," "anticipates" or "does not anticipate," "plans," "estimates" or "intends," or stating that certain actions, events or results "may," "could," "would," "might" or "will" be taken, occur or be achieved) are not statements of historical fact and may be forward-looking statements. These forward-looking statements relate to, among other things:

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our business, prospects, and overall strategy;

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progress in the development of our Demonstration Plant and the timing of that progress;

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planned or estimated expenses and capital expenditures, including the Demonstration Plant's expected costs of commissioning, operation, decommissioning, and the sources of funds to pay for such costs;

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our ability to successfully manage contractors that may be under contract with another consortium member for the Demonstration Plant project, and the risk of contractor liens on the Demonstration Plant due to contractor payment disputes we do not control;

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availability of funds and capital resources;

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our Demonstration Plant team's ability to achieve the full committed amount of funding support from the Department of Energy through the remainder of the Demonstration Plant project;

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our Demonstration Plant team's ability to secure additional funding (in addition to the previously awarded funding) relating to the Demonstration Plant project or any further initiatives or advancements that may be undertaken relating to the Demonstration Plant;

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our ability to receive the remaining uncollected funds in connection with the Wyoming Energy Authority grant for the Demonstration Plant;

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our ability to operate the Demonstration Plant, including in a manner to meet project objectives within the approved budget and estimated timeline;

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our estimates regarding the source, quality, costs, and timing of materials, equipment, supplies and resources, including human resources, for the commissioning, operation, and decommissioning of the Demonstration Plant;

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plans for our projects or other interests, operations, or rights;

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plans and strategies during and following the completion of operations of the Demonstration Plant, including the potential for further operation of the Demonstration Plant to meet additional objectives;

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plans and strategies relating to the advancement of the Bear Lodge REE Project;

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our plans and strategies to secure further funding for our longer-term business plans, including the advancement of the Bear Lodge REE Project through permitting and licensing, and, if feasible,

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ultimate construction and operations of a commercial mine and plant for processing and separation of rare earth elements;

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the timing of an amendment to the Cost Share Funding Assumption Agreement between the Company and General Atomics, whose affiliate is the Company's majority shareholder; and

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our success in obtaining, and the timing for receipts of, necessary governmental permits and approvals for our business and projects.

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Forward-looking statements are based on our current expectations and assumptions that are subject to a variety of known and unknown risks, uncertainties and other factors that could cause actual events or results to differ materially from those expressed or implied by the forward-looking statements, including, without limitation, risks associated with:

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our majority shareholder's significant influence on, or ability to control the outcome of, certain of our major corporate decisions, including our business strategies and financing options to meet our capital needs;

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our ability to protect our intellectual property rights;

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the ability of our Demonstration Plant to successfully operate and produce information that would support a decision by the Company to proceed with a potential commercial-scale production facility;

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the uncertain nature of demand for, and supply of rare earth elements, and their effect on prices for rare earth products;

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technological advancements, substitutes, and the establishment of new uses and markets for rare earth products;

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the development of new, lower cost sources of supply of rare earth products;

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development, construction and operational hazards, as well as regulatory approvals;

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our reliance on the skill and expertise of third-party service providers;

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the ability of third-party service providers to meet their contractual obligations, including as a result of supply chain disruptions and the effects those disruptions could have on our timelines and costs;

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government regulations and changes in legislation and regulations relating to the mining and rare earth industries, including environmental laws and regulations that impose material compliance costs and liabilities;

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difficulty in obtaining necessary governmental permits, licenses, and approvals for our Bear Lodge REE Project;

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governmental interventions in the mining and rare earth industries, including increases in barriers to domestic production and international trade;

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the impact of potential new and/or increased tariffs and other trade restrictions on the global trade industry;

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uncertainties regarding our ability to maintain sufficient liquidity and attract sufficient capital resources to implement our projects and strategies;

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our ability to attract and retain key personnel;

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the impact of inflation on our business, including the costs of and our ability to complete the Demonstration Plant commissioning, operations and decommissioning, and the Bear Lodge REE Project;

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the impact of external financial sector factors, including the security of our bank and investment account deposits;

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uncertainties inherent in estimates of future operating results;

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changes in competitive factors, including the development or expansion of other projects that are competitive with ours;

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China's dominance of the rare earth supply chain and its ability to significantly impact market supply, demand and prices;

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our ability to complete financings and other transactions;

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pandemics, epidemics or other disease outbreaks on supply chains and any resulting disease containment measures implemented by various governments;

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the availability and costs of goods and services we need to achieve our plans and goals resulting from military conflicts or wars such as in Russia/Ukraine and the Middle East;

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information technology system and/or data disruptions, damage, theft, failures, or cyber-attacks;

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uncertainties associated with litigation matters and opposition to our plans and operations by third parties;

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share price volatility;

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whether we deregister our common shares under the Exchange Act and/or list our common shares on a securities exchange other than the QTCQB Venture Marketplace;

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foreign and domestic government actions impacting the pricing for, or supply of, rare earth products, including changes in the actual or perceived supply and demand for rare earths due to foreign government export controls;

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the OTCQB Venture Marketplace standards and the "penny stock" rules and the impact on trading volume and liquidity due to our trading on the OTCQB Venture Marketplace;

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the consequences of Synchron, the Company's majority shareholder, discontinuing its support for the Company;

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risk factors discussed in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024; and

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other factors, many of which are beyond our control.

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This list is not exhaustive of the factors that might affect our forward-looking statements. Some of the important risks and uncertainties that could affect forward-looking statements are described further under the "Risk Factors" sections of this prospectus supplement and our filings with the SEC incorporated by reference in this prospectus supplement. Although we have attempted to identify important factors that could cause actual results to differ materially from those described in forward-looking statements, there may be other factors that could cause results not to be as anticipated, estimated or intended. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those anticipated, believed, estimated or expected. We caution readers not to place undue reliance on any such forward-looking statements, which speak only as of the date made. Except as required by law, we disclaim any obligation to revise or update any forward-looking statements to reflect events or circumstances after the date of such statements or to reflect the occurrence of anticipated or unanticipated events. We qualify all of the forward-looking statements contained or incorporated by reference in this prospectus supplement by the foregoing cautionary statements.

RISK FACTORS

Prospective investors should carefully consider the following risk factors, together with the other information contained in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein, in evaluating the Company and its business before purchasing our securities. In particular, prospective investors should note that this prospectus supplement and the accompanying prospectus contain forward-looking statements within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act, and that actual results could differ materially from those contemplated by such statements. The risk factors listed below, in the accompanying prospectus and in the documents incorporated by reference herein and therein represent certain important factors which we believe could cause such results to differ. These risk factors are not intended to represent a complete list of the general or specific risks that may affect us. It should be recognized that other risks may be significant, presently or in the future, and the risks set forth below may affect us to a greater extent than indicated.

Risks Relating to this Rights Offering

Regardless of the extent to which Synchron and holders other than Synchron exercise their subscription rights, Synchron will continue to hold more than 50% of our outstanding common shares after the rights offering, and as a result you may have reduced liquidity for your common shares. This is the case whether or not you exercise your subscription rights because you have no control over the exercise of subscription rights by other holders.

Synchron, which held approximately 70% of our common shares outstanding as of January 30, 2026, has advised the Company that it intends to participate in the rights offering, but Synchron has not entered into any written or verbal agreement or other arrangement with the Company to do so, nor has Synchron indicated the circumstances under which it would participate in the rights offering. Depending on the extent to which Synchron and holders other than Synchron exercise their subscription rights, after giving effect to this rights offering, Synchron's ownership percentage in our outstanding common shares could be anywhere between approximately 56% and approximately 76% upon completion of the rights offering. Participation in the Company's December 2021 rights offering by Synchron and holders other than Synchron was approximately 62% and 38%, respectively, resulting in Synchron's ownership increasing from approximately 48% before the rights offering to approximately 55% after the rights offering. Participation in the Company's February 2024 rights offering by Synchron and holders other than Synchron was approximately 82% and 18%, respectively, resulting in Synchron's ownership increasing from approximately 55% before the rights offering to approximately 71% after the rights offering. If Synchron declines to participate in the rights offering, but all other shareholders exercise their subscription privileges in full, then Synchron's ownership percentage would be reduced to approximately 56% after the rights offering. However, if Synchron exercises its basic subscription and oversubscription privileges in full but no other shareholder exercises its subscription privileges, then Synchron's ownership percentage would be increased to approximately 76% after the rights offering. If Synchron and holders other than Synchron participate in the rights offering at levels similar to those in the Company's December 2021 rights offering (i.e., by purchasing approximately 62% and 38%, respectively, of the common shares issued in the rights offering, assuming it is fully subscribed), then Synchron's ownership percentage would be reduced to approximately 68% after the rights offering. If Synchron and holders other than Synchron participate in the rights offering at levels similar to those in the Company's February 2024 rights offering (i.e., by purchasing approximately 82% and 18%, respectively, of the common shares issued in the rights offering, assuming it is fully subscribed), then Synchron's ownership percentage would be increased to approximately 72% after the rights offering. We believe Synchron will hold greater than 70% of our common shares after the rights offering. As a holder of greater than 50% of our outstanding common shares, Synchron is able to exercise control over all matters requiring shareholder approval, including the election of directors, mergers, consolidations and acquisitions, the sale of all or substantially all of our assets and other decisions affecting our capital structure, amendments to our certificate of incorporation and articles, and our winding up and dissolution. In addition, pursuant to the Investment Agreement, absent a waiver approved by our board of directors with the concurrence of a majority of Synchron's designees on the board, we may not authorize the issuance of additional shares of capital stock without the approval of the holders of a majority of our outstanding common shares. If Synchron's ownership percentage increases as a result of the proposed rights offering, then Synchron's control over the foregoing matters would be further reinforced. Your interests as a holder of common shares may differ from the interests of Synchron.

A substantial number of our shares will be available for future sale, which could depress the market price of our common shares.

As of January 30, 2026, the record date, there were 516,134,712 common shares outstanding. Upon exercise of all subscription rights offered hereunder, 645,168,390 common shares would be outstanding. In addition, as of September 30, 2025, there were outstanding options to purchase an aggregate 3,705,000 common shares.

We will require additional capital resources to progress with the feasibility studies, licensing, permitting, development and construction related to the Bear Lodge REE Project, for which we may seek to enter into strategic agreements, joint ventures or similar agreements or we may sell additional equity or debt in public or private transactions. Such transactions may include private offerings, underwritten or "best efforts" offerings to the public or additional rights offerings to current shareholders. Sales of large amounts of our common shares in the market could adversely affect the market price of our common shares. All of these events could have a material adverse impact on the market price of our common shares and could impair our future ability to raise capital through offerings of our securities at a time and price that we deem appropriate.

The subscription price determined for the rights offering is not an indication of the fair value of our common shares.

The subscription price in the rights offering is equal to $0.24, which is significantly lower than the $0.83 closing price of our common shares on January 6, 2026, immediately preceding our January 6, 2026 announcement of the Company's intent to launch a rights offering at the subscription price. The subscription price does not necessarily bear any relationship to the book value of our assets, net worth, past operations, cash flows, losses, financial condition, or any other established criteria for valuing the Company. You should not consider the subscription price an indication of the value of the Company or our common shares. You should not assume or expect that, after the rights offering, our common shares will trade at or above the subscription price. We can give no assurance that our common shares will trade at or above the subscription price in any given time period.

You may not revoke your subscription exercise, even if the rights offering is extended, and your purchase of shares in the rights offering may be at a price higher than the market price.

Except in the event that we make a fundamental change to the terms and conditions of the rights offering, once you exercise your subscription rights, you may not revoke the exercise. If we decide to extend the duration of the rights offering, you still may not revoke the exercise of your subscription rights. The public trading market price of our common shares may decline before the subscription rights expire. If you exercise your subscription rights and, afterwards, the market price of our common shares falls below the subscription price, then you will have committed to buy common shares in the rights offering at a price that is higher than the market price. Moreover, we cannot assure you that you will ever be able to sell common shares that you purchased in the rights offering at a price equal to or greater than the subscription price. Until certificates are delivered or your account at your broker, dealer, custodian bank or other nominee is credited upon expiration of the rights offering, you may not be able to sell the common shares that you purchase in the rights offering. We will issue certificates representing our common shares, or credit your account at your broker, dealer, custodian bank or other nominee with our common shares, electronically in registered, book-entry form only on our records or on the records of our transfer agent, Computershare Trust Company of Canada, that you purchased pursuant to your basic subscription and oversubscription privileges as soon as practicable after the rights offering has expired and all proration calculations, reductions, and additions contemplated by the terms of the rights offering have been effected.

Because we do not have formal commitments from any of our shareholders to participate in the rights offering and because no minimum subscription is required, we cannot assure you of the amount of proceeds, if any, that we will receive from the rights offering.

We do not have formal commitments from any of our shareholders to participate in the rights offering and no minimum subscription is required for consummation of the rights offering. Synchron, the majority shareholder of the Company, has advised the Company that it intends to participate in the rights offering, but

Synchron has not entered into any written or verbal agreement or other arrangement with the Company to do so, nor has Synchron indicated the circumstances under which it would participate in the rights offering. We cannot assure you that any of our shareholders will exercise all or any part of their subscription rights, and as a result, we cannot assure you of the amount of proceeds that we will receive in the rights offering. Therefore, if you exercise all or any portion of your subscription rights, but other shareholders do not, we may not raise the desired amount of capital in this rights offering, the market price of our common shares could be adversely impacted and we may find it necessary to pursue alternative means of financing, which may be dilutive to your investment.

Because we may terminate the offering at any time prior to 5:00 p.m., Eastern Time, on the expiration date, your participation in the rights offering is not assured.

We do not intend, but have the right, to terminate the offering at any time prior to 5:00 p.m., Eastern Time, on the expiration date. If we determine to terminate the offering, we will not have any obligation with respect to the subscription rights except to return any money received from subscribing shareholders as soon as practicable, without interest or deduction.

You will need to act promptly and carefully follow the subscription instructions, or your exercise of subscription rights will be rejected.

Shareholders who desire to purchase shares in this rights offering must act promptly to ensure that all required forms and payments are actually received by the subscription agent prior to 5:00 p.m., Eastern Time, on March 4, 2026, the expected expiration date. If you are a beneficial owner of shares, you must act promptly to ensure that your broker, dealer, custodian bank or other nominee acts for you and that all required forms and payments are actually received by the subscription agent prior to 5:00 p.m., Eastern Time, on the expiration date of the subscription period. We are not responsible if your broker, dealer, custodian bank or other nominee fails to ensure that all required forms and payments are actually received by the subscription agent prior to the expiration date. If you fail to complete and sign the required subscription forms, or you send an incorrect payment amount, or your payment does not clear, or you otherwise fail to follow the subscription procedures that apply to your exercise in this rights offering prior to 5:00 p.m., Eastern Time, on the expiration date, the subscription agent may, depending on the circumstances, reject your subscription or accept it only to the extent of the payment received. Neither we nor our subscription agent will undertake to contact you concerning, or attempt to correct, an incomplete or incorrect subscription form or payment. We have the sole discretion to determine whether a subscription exercise properly follows the subscription procedures.

You will not receive interest on subscription funds, including any funds ultimately returned to you.

You will not earn any interest on your subscription funds while they are being held by the subscription agent pending the closing of this rights offering. In addition, if we cancel the rights offering or if you exercise your oversubscription privilege and are not allocated all of the common shares for which you oversubscribe, neither we nor the subscription agent will have any obligation with respect to the subscription rights except to return, without interest or deduction, any subscription payments to you as soon as practicable.

You may not receive all of the shares you subscribe for pursuant to the oversubscription privilege.

If an insufficient number of shares are available to fully satisfy all oversubscription privilege requests, the available shares will be distributed proportionately among shareholders who properly exercised their oversubscription privileges based on the number of shares each shareholder subscribed for under its basic subscription privilege.

We may amend or modify the terms of the rights offering at any time before the expiration of the rights offering in a manner that could adversely affect your investment.

Our board of directors reserves the right to amend or modify the terms of the rights offering. The amendments or modifications may be made for any reason. If we make any fundamental change to the terms of the rights offering after the filing of this prospectus supplement, we will file a post-effective amendment to this prospectus supplement and offer subscribers the opportunity to cancel their subscriptions.

In such event, we will issue subscription refunds to each shareholder subscribing to purchase shares in the rights offering and recirculate an amended prospectus supplement. If we extend the expiration date of the rights offering period in connection with any post-effective amendment, we will allow holders of rights a reasonable period of additional time to make new investment decisions on the basis of the new information set forth in the amended prospectus supplement. In such event, we will issue a press release announcing the changes to the rights offering and the new expiration date. Even if an amendment does not rise to the level that is fundamental and would thus require us to offer to return your subscription payment, the amendment may nonetheless adversely affect your rights and any prospective return on your investment.

You may not be able to resell any of our common shares that you purchase pursuant to the exercise of subscription rights until you or your broker, dealer, custodian bank or other nominee receives the shares or be able to sell your shares at a price equal to or greater than the subscription price.

If you exercise your subscription rights, you may not be able to resell the underlying common shares until you or your broker, dealer, custodian bank or other nominee, if applicable, have received those shares. Moreover, you will have no rights as a holder of the common shares that you purchased in this rights offering until we issue the shares to you. In addition, we cannot assure you that, following the exercise of your subscription rights, you will be able to sell your common shares at a price equal to or greater than the subscription price.

If you do not fully exercise your subscription right, your interest in us will be substantially diluted if and to the extent other shareholders fully exercise their basic subscription and oversubscription privileges. In addition, if you do not exercise your subscription rights in full and the subscription price is less than the fair value of our common shares, then you would experience an immediate dilution of the aggregate fair value of your shares, which could be substantial.

If you do not choose to fully exercise your subscription rights, your percentage ownership interest in us will decrease if and to the extent other shareholders fully exercise their basic subscription and oversubscription privileges. If you do not exercise your subscription rights at all, your percentage ownership in us could decrease substantially if and to the extent other shareholders fully exercise their basic subscription and oversubscription privileges. In addition, if you do not exercise your subscription rights in full and the subscription price is less than the fair value of our common shares, you would experience immediate dilution of the value of your shares relative to what your value would have been had our common shares been issued at fair value. This dilution could be substantial.

Future sales of our common shares by our insiders may cause our share price to decline.

A portion of our outstanding shares are held by directors and executive officers. Resales of a substantial number of shares of our shares by these shareholders, announcements of the proposed resale of substantial amounts of our shares, or the perception that substantial resales may be made by such shareholders could adversely impact the market price of our shares. Actual or potential sales by these insiders may adversely impact the market price of our shares.

The receipt of subscription rights may be treated as a taxable distribution to U.S. holders of our common shares.

It is the opinion of U.S. federal income tax counsel that the distribution of the subscription rights in this rights offering should, for U.S. federal income tax purposes, be a non-taxable distribution to U.S. holders of our common shares under Section 305(a) of the Internal Revenue Code of 1986, as amended, or the Code. However, this position is not binding on the Internal Revenue Service, or the courts. If, contrary to U.S. federal income tax counsel's conclusion and corresponding opinion hereunder that the distribution of the subscription rights in this rights offering should be a non-taxable event, the rights offering is deemed to be part of a "disproportionate distribution" under Section 305 of the Code, the receipt of subscription rights by a U.S. holder of our common shares may be treated as the receipt of a taxable distribution equal to the fair market value of the subscription rights. For a detailed discussion, please see "Material United States Federal Income Tax Consequences." Each U.S. holder of our common shares is urged to consult his, her or its own tax advisor with respect to the tax consequences of the rights offering.

Our net operating losses may be limited for United States federal income tax purposes as a result of the rights offering.

Section 382 of the Code imposes a limitation on a corporation's use of net operating loss ("NOL") carryforwards for United States federal income tax purposes if the corporation has undergone an "ownership change." Depending on a number of circumstances, including the extent to which the subscription rights are exercised out of proportion to our existing common share ownership, the exercise of subscription rights pursuant to the rights offering, when combined with certain other shifts in ownership of our common shares involving one or more "5% shareholders" during the "testing period" ​(generally the three years preceding the testing date), may create an ownership change in us for purposes of Section 382 and therefore result in an annual limitation on the use of our NOL carryforwards. Because we have taken a full valuation allowance for our deferred tax assets on our financial statements, an ownership change would not have an immediate impact on our reported earnings for financial accounting purposes but may cause significant limitation on our use of the NOL carryforwards in future years to offset our taxable income.

USE OF PROCEEDS

If we sell all the common shares being offered in this rights offering, we expect the total gross proceeds to be approximately $30.9 million and net proceeds, after deducting estimated fees and expenses, to be approximately $30.5 million.

The net proceeds will be used (i) to support (A) the continuation of the operation of the Demonstration Plant; (B) the advancement of projects for the as-constructed Demonstration Plant beyond the current neodymium/praseodymium (Nd/Pr) separation objectives, including applying the technology to the separation of heavy rare earth elements and to third-party feed sources; and (C) the completion of federal and state permitting and licensing for the Bear Lodge REE Project; and (ii) for other general corporate purposes. Pending the application of the net proceeds from this rights offering, we intend to invest such proceeds in short-term interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the U.S. government.

We will bear all of the expenses of this rights offering, and such expenses will be paid out of our general funds.

The Company intends to spend the net proceeds from the rights offering as stated below, assuming that different amounts of gross proceeds are raised in the offering. The Company will reallocate funds only for sound business reasons.

​

(1)

In order to support the advancement of the Bear Lodge REE Project, including the operation of the Demonstration Plant, for the purposes stated above, the rights offering would need to raise net proceeds of approximately $30.5 million. In the event the net proceeds of the rights offering are less than approximately $30.5 million, or 100% of the maximum size of the rights offering, the Company would need to seek additional funding to progress the stated objectives. There is no assurance that the Company will be able to raise additional funds on a timely basis or at all.

​

THE RIGHTS OFFERING

The Subscription Rights

We are distributing to holders of our common shares at the close of business on the record date, which is January 30, 2026, at no charge, twenty-five hundredths (or 0.25) of a non-transferable subscription right for each of our common shares owned by such holders as of the close of business on the record date. Each whole subscription right shall consist of (i) a basic subscription privilege to purchase one common share at a subscription price of $0.24 per share and (ii) if the basic subscription privilege is exercised in full by a holder thereof, an oversubscription privilege to subscribe for an unlimited number of whole common shares at the subscription price that are not purchased by other holders, subject to (A) a maximum of 129,033,678 common shares and (B) the allocation among all holders properly exercising the oversubscription privilege. As of January 30, 2026, there were 516,134,712 common shares outstanding.

Basic Subscription Privilege

The subscription rights are evidenced by non-transferable rights certificates. Each whole subscription right entitles the holder to purchase one of our common shares upon delivery of the required subscription documents and payment of the subscription price of $0.24 per share prior to 5:00 p.m., Eastern Time, on the expiration date of the rights offering.

You may exercise all or a portion of your basic subscription privilege or you may choose not to exercise your rights. However, if you exercise less than your full basic subscription privilege, you will not be entitled to purchase shares pursuant to your oversubscription privilege. In order to properly exercise your basic subscription privilege, you must deliver the subscription payment and a properly completed rights certificate, or if you hold your rights through a broker, dealer, custodian bank or other nominee, complete and return to your record holder the form entitled "Beneficial Owner Election Form" or such other appropriate documents as are provided by your record holder.

We will not issue fractional common shares in the rights offering. Any excess subscription payment received by the subscription agent will be returned, without interest or deduction, as soon as practicable after the expiration of the subscription period. We will deliver certificates representing our common shares or credit your account at your broker, dealer, custodian bank or other nominee with our common shares, electronically in registered, book-entry form, purchased with the basic subscription privilege as soon as practicable.

Oversubscription Privilege

If you exercise your basic subscription privilege in full, you may also exercise an oversubscription privilege to purchase additional common shares that are not purchased by other rights holders pursuant to their basic subscription privileges, at the same subscription price of $0.24 per share. You are entitled to exercise your oversubscription privilege only if you exercise your basic subscription privilege in full.

As an illustrative example, if you own 1,000 of the Company's common shares on the record date, you will receive subscription rights under the basic subscription privilege enabling you to purchase up to 250 common shares at $0.24 per share. If you exercise your basic subscription privilege to purchase all (but not less than all) of the 250 common shares, you could also exercise your oversubscription privilege to purchase additional common shares that remain unsubscribed for as a result of any other shareholders not exercising their basic subscription privilege, subject to the pro rata allocation of shares among rights holders properly exercising their oversubscription privilege.

In order to properly exercise your oversubscription privilege, you must deliver the subscription payment and a properly completed rights certificate, or if you hold your rights through a broker, dealer, custodian bank or other nominee, complete and return to your record holder the form entitled "Beneficial Owner Election Form" or such other appropriate documents as are provided by your record holder. Because we will not know the total number of unsubscribed shares prior to the expiration of the rights offering, if you wish to maximize the number of shares that you purchase pursuant to your oversubscription privilege, you will need to deliver payment in an amount equal to the aggregate subscription price for the maximum

number of our common shares available to you under the oversubscription privilege, assuming that no shareholder other than you has purchased any our common shares pursuant to his, her or its basic subscription privilege and oversubscription privilege.

We can provide no assurances that you will actually be entitled to purchase the number of shares issuable upon the exercise of your oversubscription privilege in full at the expiration of the rights offering. We will not be able to satisfy your exercise of the oversubscription privilege if the rights offering is subscribed in full, and we will only honor an oversubscription privilege to the extent sufficient common shares are available following the exercise of subscription rights under the basic subscription privilege.

If an insufficient number of shares is available to fully satisfy all oversubscription privilege requests, the available shares will be distributed proportionately among shareholders who properly exercised their oversubscription privileges based on the number of shares each shareholder subscribed for under its basic subscription privilege. If the holders of subscription rights properly exercise their oversubscription privilege for an aggregate amount of shares that is less than or equal to the number of unsubscribed shares, you will be allocated the number of unsubscribed shares for which you actually paid in connection with the oversubscription privilege. Each holder that exercises its basic subscription privilege in full may subscribe for a number of additional common shares equal to the lesser of (1) the number of shares subscribed for by the holder under the oversubscription privilege and (2) the number calculated in accordance with the following formula: x(y/z), where x = the aggregate number of common shares available through unexercised rights after giving effect to the basic subscription privilege; y = the number of rights exercised by the holder under the basic subscription privilege; and z = the aggregate number of rights exercised under the basic subscription privilege by holders of the rights that have subscribed for common shares under the oversubscription privilege. To the extent that the number of subscription rights that are distributed to you on the record date is not a whole number, the common shares issuable upon exercise of the basic subscription or oversubscription privilege will be rounded down to the nearest whole share for purposes of determining the number of our common shares for which you may subscribe. The subscription agent will return any excess payments without interest or deduction as soon as practicable after the expiration of the rights offering.

As soon as practicable after the expiration date, the subscription agent will determine the number of common shares that you may purchase pursuant to the oversubscription privilege. We will issue certificates representing your common shares, or credit your account at your broker, dealer, custodian bank or other nominee with your common shares, electronically in registered, book-entry form only on our records or on the records of our transfer agent, Computershare Trust Company of Canada, that you purchased pursuant to your basic subscription and oversubscription privileges as soon as practicable after the rights offering has expired and all proration calculations, reductions, and additions contemplated by the terms of the rights offering have been effected. If you request and pay for more shares than are allocated to you, the subscription agent will return any excess payments by mail, without interest or deduction as soon as practicable after the expiration of the subscription period. In connection with the exercise of the oversubscription privilege, brokers, dealers, custodian banks and other nominee holders of subscription rights who act on behalf of beneficial owners will be required to certify to us and to the subscription agent as to the aggregate number of subscription rights exercised, and the number of common shares requested through the oversubscription privilege, by each beneficial owner on whose behalf the nominee holder is acting.

Missing or Incomplete Subscription Information

If you do not indicate the number of subscription rights being exercised, or the subscription agent does not receive the full subscription payment for the number of subscription rights that you indicate are being exercised, then you will be deemed to have exercised the maximum number of subscription rights that may be exercised with the aggregate subscription payment you delivered to the subscription agent. If we do not apply your full subscription payment to your purchase of our common shares, the subscription agent will return any excess subscription payment received without interest or deduction, as soon as practicable after the expiration of the subscription period.

Expiration of the Rights Offering and Amendments, Extensions and Termination

You may exercise your subscription rights at any time prior to 5:00 p.m., Eastern Time, on March 4, 2026, the expected expiration date for the rights offering, subject to extension until a date no later than

March 6, 2026. If you do not exercise your subscription rights before the expiration date of the rights offering, your subscription rights will expire and will have no value. We will not be required to issue our common shares to you if the subscription agent receives your rights certificate or payment, after the expiration date, regardless of when you sent the rights certificate and payment. We may choose to extend the rights offering at any time after the record date. If we elect to extend the expiration date of the rights offering, terminate the rights offering prior to 5:00 p.m., Eastern Time, on the expiration date or amend or modify the terms of the rights offering, we will issue a press release announcing such extension, termination or amendment or modification.

We reserve the right, in our sole discretion, to amend or modify the terms of the rights offering. The amendments or modifications may be made for any reason. If we make any fundamental change to the terms of the rights offering after the filing of this prospectus supplement, we will file a post-effective amendment to this prospectus supplement and offer subscribers the opportunity to cancel their subscriptions. In such event, we will issue subscription refunds to each shareholder subscribing to purchase shares in the rights offering and recirculate an amended prospectus supplement. If we extend the expiration date of the rights offering period in connection with any post-effective amendment, we will allow holders of rights a reasonable period of additional time to make new investment decisions on the basis of the new information set forth in the amended prospectus supplement. In such event, we will issue a press release announcing the changes to the rights offering and the new rights offering expiration date. The terms and conditions of the rights offering cannot be modified or amended after the expiration date.

We also reserve the right to terminate the rights offering at any time prior to 5:00 p.m., Eastern Time, on the expiration date for any reason. In the event the rights offering is terminated, the subscription agent will return all subscription funds without interest or deduction.

Conditions to and Cancellation of the Rights Offering

Your exercise of subscription rights is not subject to the satisfaction of any conditions. However, we reserve the right to amend, extend, cancel, terminate or otherwise modify the rights offering at any time before completion of the rights offering for any reason. In the event that we terminate the rights offering prior to 5:00 p.m., Eastern Time, on the expiration date, all affected subscription rights will expire without value and all subscription payments received by the subscription agent will be returned as soon as practicable, without interest or deduction. If we elect to extend the expiration date of the rights offering, terminate the rights offering prior to 5:00 p.m., Eastern Time, on the expiration date or amend or modify the terms of the rights offering, we will issue a press release announcing such extension, termination or amendment or modification. Please see "- Expiration of the Rights Offering and Amendments, Extension and Termination."

Method of Exercising Subscription Rights

Except in the event that we make a fundamental change to the terms and conditions of the rights offering, the exercise of subscription rights is irrevocable and may not be cancelled or modified. Your subscription rights will not be considered exercised unless the subscription agent receives from you, your broker, dealer, custodian bank or other nominee, as the case may be, all of the required documents properly completed and executed and your full subscription price payment in cash prior to 5:00 p.m., Eastern Time, on March 4, 2026, the expected expiration date of the rights offering. Rights holders may exercise their rights as follows:

Subscription by Record Holders

Rights holders who are record holders of our common shares may exercise their subscription rights by properly completing and executing the rights certificate together with any required signature guarantees and forwarding it, together with payment in full in cash, of the subscription price for each of the common shares for which they subscribe, to the subscription agent at the address set forth under the subsection entitled "- Delivery of Subscription Materials and Payment," prior to 5:00 p.m., Eastern Time, on the expiration date.

Subscription by Beneficial Owners

Rights holders who are beneficial owners of our common shares and whose shares are registered in the name of a broker, dealer, custodian bank or other nominee, and rights holders who hold common share certificates and would prefer to have an institution conduct the transaction relating to the rights on their behalf, should instruct their broker, dealer, custodian bank or other nominee to exercise their rights and deliver all documents and payment on their behalf, prior to 5:00 p.m., Eastern Time, on the expiration date. A rights holder's subscription rights will not be considered exercised unless the subscription agent receives from such rights holder, its broker, dealer, custodian bank or other nominee or institution, as the case may be, all of the required documents and such holder's full subscription price payment.

Subscription by DTC and CDS Participants

Banks, trust companies, securities dealers and brokers that hold our common shares as nominee for more than one beneficial owner may, upon proper showing to the subscription agent, exercise their subscription rights on the same basis as if the beneficial owners were record holders on the rights offering record date through DTC or CDS Clearing and Depository Services Inc. ("CDS"). Such holders may exercise these rights through DTC's and CDS's electronic book entry and settlement processes, following instructions given by their DTC or CDS participant. DTC or CDS, as applicable, must receive the subscription instructions and payment for the new shares by the rights offering expiration date.

Payment Method

Payments must be made in full in U.S. currency to the subscription agent by certified check, bank draft or money order payable to "Computershare Investor Services Inc."

Rights certificates received after 5:00 p.m., Eastern Time, on March 4, 2026, the expected expiration date of the rights offering, will not be honored, and we will return your payment to you as soon as practicable, without interest or deduction. The subscription agent will be deemed to receive payment upon receipt of payment in full, for both the basic subscription and oversubscription, if applicable, in the form of certified check, bank draft or money order.

You should read the instruction letter accompanying the rights certificate carefully and strictly follow it. DO NOT SEND RIGHTS CERTIFICATES OR PAYMENTS TO US. We will not consider your subscription received until the subscription agent has received delivery of a properly completed and duly executed rights certificate and payment of the full subscription amount. The risk of delivery of all documents and payments is on you or your broker, dealer, custodian bank or other nominee, not us or the subscription agent.

The method of delivery of rights certificates and payment of the subscription amount to the subscription agent will be at the risk of the holders of rights, but, if sent by mail, we recommend that you send those certificates and payments by overnight courier or by registered mail, properly insured, with return receipt requested, and that a sufficient number of days be allowed to ensure delivery to the subscription agent and clearance of payment before the expiration of the subscription period.

Unless a rights certificate provides that the common shares are to be delivered to the record holder of such rights or such certificate is submitted for the account of a bank or a broker, signatures on such rights certificate must be guaranteed by an "Eligible Guarantor Institution," as such term is defined in Rule 17Ad-15 of the Exchange Act, subject to any standards and procedures adopted by the subscription agent. Please see "- Medallion Guarantee May Be Required."

Medallion Guarantee May Be Required

Your signature on each subscription rights certificate must be guaranteed by an eligible institution, such as a member firm of a registered national securities exchange or a member of the Financial Industry Regulatory Authority, or a commercial bank or trust company having an office or correspondent in the United States, subject to standards and procedures adopted by the subscription agent, unless your subscription rights certificate provides that shares are to be delivered to you as record holder of those subscription rights.

Subscription Agent

The subscription agent for this rights offering is Computershare Investor Services Inc. We will pay all fees and expenses of the subscription agent related to the rights offering and have also agreed to indemnify the subscription agent from certain liabilities that they may incur in connection with the rights offering.

Delivery of Subscription Materials and Payment

If your shares are held in the name of a broker, dealer, custodian bank or other nominee, then you should send your subscription documents, rights certificate, such other documents requested by your nominee and payment of the subscription price to your broker, dealer, custodian bank or other nominee. If you are the record holder of your shares, then you should deliver your subscription rights certificate and payment of the subscription price in cash, as provided in this prospectus supplement, to the subscription agent by hand delivery, overnight courier or first-class mail at the following address:

By Hand or Overnight Courier:
Computershare Investor Services Inc.
Attn: Corporate Actions
320 Bay Street, 14th Floor
Toronto, Ontario M5H 4A6
Phone Number (domestic): 1-800-564-6253

By Mail:
Computershare Investor Services Inc.
Attn: Corporate Actions
P.O. Box 7021
31 Adelaide Street East
Toronto, Ontario M5C 3H2
Phone Number (domestic): 1-800-564-6253

Your delivery other than in the manner or to the address listed above will not constitute valid delivery.

You should direct any questions or requests for assistance concerning the method of subscribing for the common shares or for additional copies of this prospectus supplement and the accompanying prospectus to the subscription agent, whose contact information is provided above.

Escrow Arrangements

The subscription agent will hold funds received in payment of the subscription price in a segregated account until the rights offering is completed or withdrawn and terminated.

If there is a fundamental change to the rights offering and if you decide to cancel your subscription rights, then the subscription agent will return your payment without charge of any interest, penalties or deductions. If you hold your shares through your broker, dealer, custodian bank or other nominee, then the cancellation of any subscription rights would have to be initiated by your broker, dealer, custodian bank or other nominee.

If the subscription agent returns payments to you through your broker, dealer, custodian bank or other nominee, then such broker, dealer, custodian bank or other nominee may charge you separate service or administration fees. We are not responsible for covering or reimbursing any such fees.

Notice to Beneficial Holders

If you are a broker, dealer, custodian bank or other nominee holder that holds our common shares for the account of others as of the record date, you should notify the respective beneficial owners of such shares of this rights offering as soon as possible to learn their intentions with respect to exercising their subscription rights. You should obtain instructions from the beneficial owners with respect to their subscription rights, as set forth in the instructions we have provided to you for your distribution to beneficial owners. If the beneficial owner so instructs, you should complete the appropriate subscription rights certificates and submit

them to the subscription agent with the proper payment. If you hold our common shares for the account(s) of more than one beneficial owner, you may exercise the number of subscription rights to which all such beneficial owners in the aggregate otherwise would have been entitled had they been direct record holders of our common shares on the record date, provided that you, as a nominee record holder, make a proper showing to the subscription agent by submitting the form entitled "Nominee Holder Certification" that we will provide to you with your rights offering materials. If you did not receive this form, you should contact the subscription agent to request a copy.

Beneficial Owners

If you are a beneficial owner of our common shares or will receive subscription rights through a broker, dealer, custodian bank or other nominee, we will ask your broker, dealer, custodian bank or other nominee to notify you of the rights offering. If you wish to exercise your subscription rights, you will need to have your broker, dealer, custodian bank or other nominee act for you. If you hold certificates of our common shares directly and would prefer to have your broker, dealer, custodian bank or other nominee act for you, you should contact your broker, dealer, custodian bank or other nominee and request it to effect the transactions for you. To indicate your decision with respect to your subscription rights, you should complete and return to your broker, dealer, custodian bank or other nominee the form entitled "Beneficial Owner Election Form" or such other appropriate documents as are provided by your broker, dealer, custodian bank or other nominee. You should receive the "Beneficial Owner Election Form" or other appropriate documents from your broker, dealer, custodian bank or other nominee with the other rights offering materials. If you wish to obtain a separate subscription rights certificate, you should contact the nominee as soon as possible and request that a separate subscription rights certificate be issued to you. You should contact your broker, dealer, custodian bank or other nominee if you do not receive this form but you believe that you are entitled to participate in the rights offering. We are not responsible if you do not receive this form from your broker, dealer, custodian bank or other nominee or if you receive it without sufficient time to respond.

Reasons for the Rights Offering

In authorizing the rights offering, the members of our board of directors who are not Synchron director designees carefully evaluated our need for liquidity, financial flexibility and additional capital. The members of our board of directors who are not Synchron director designees considered several alternative capital raising methods, including through cost-sharing opportunities and loan programs with government agencies, private placements of equity and equity-linked securities, and other transactions. After considering these various capital raising methods, the board concluded that the rights offering was the appropriate alternative in the circumstances for a number of reasons, including that the rights offering (i) affords an opportunity to our shareholders to participate on a pro rata basis, (ii) is a capital raising method that the Company successfully utilized in December 2021 and February 2024, and (iii) provides a structure for the Company to raise sufficient capital for the intended use of proceeds on a timely basis. In accordance with the terms of the Investment Agreement between the Company and Synchron, the Company obtained a waiver approved by our board of directors (with the concurrence of a majority of Synchron's designees on the board) to authorize the issuance of additional common shares pursuant to the rights offering.

We are conducting the rights offering to raise capital (i) to support (A) the continuation of the operation of the Demonstration Plant; (B) the advancement of projects for the as-constructed Demonstration Plant beyond the current neodymium/praseodymium (Nd/Pr) separation objectives, including applying the technology to the separation of heavy rare earth elements and to third-party feed sources; and (C) the completion of federal and state permitting and licensing for the Bear Lodge REE Project; and (ii) for other general corporate purposes.

Subscription Price

In determining the subscription price, our board of directors considered a number of factors, including the likelihood of obtaining (and the likely cost of) capital from other sources, the restrictions under the Investment Agreement on our ability to issue shares, the price at which our shareholders might be willing to participate in the rights offering, the likelihood of achieving a high level of shareholder participation in the offering, the historical and current trading prices of our common shares, the discount to market value

represented by the subscription price in the Company's December 2021 and February 2024 rights offerings, our need for liquidity and the desire to provide an opportunity to our shareholders to participate in the rights offering on a pro rata basis. In conjunction with its review of these factors, our board of directors also reviewed a range of discounts to market value represented by the subscription prices in various prior rights offerings of public companies.

The matters considered by the members of our board of directors who are not Synchron director designees included discussions with Synchron, the majority shareholder of the Company, as to a subscription price at which Synchron might participate in the rights offering, although Synchron has not entered into any written or verbal agreement or other arrangement with the Company in respect of such participation. As noted above, the Investment Agreement places significant restrictions on the ability of the Company to issue shares of its capital stock. The Investment Agreement provides that absent a waiver approved by our board of directors with the concurrence of a majority of Synchron's designees on the board, we may not authorize the issuance of additional shares of capital stock without the approval of the holders of a majority of our common shares then outstanding. In connection with the consideration of a rights offering by our board of directors, the concurrence with such waiver by the majority of Synchron's designees on the board was conditioned upon the terms of the proposed rights offering being as set forth in this prospectus supplement, including with respect to the subscription price. Without the concurrence with such waiver by the majority of Synchron's designees on our board, the Company would have needed the approval of the holders of the majority of the common shares outstanding to approve the rights offering.

After consideration of all of these factors, the subscription price was established at a price of $0.24 per share. The subscription price does not necessarily bear any relationship to the book value of our assets, net worth, past operations, cash flows, losses, financial condition, or any other established criteria for valuing the Company. You should not consider the subscription price as an indication of the value of the Company or our common shares. You should not assume or expect that, after the rights offering, our common shares will trade at or above the subscription price. We also cannot assure you that the market price of our common shares will not decline during or after the rights offering. We urge you to obtain a current quote for our common shares before exercising your subscription rights.

Determination Regarding the Exercise of Your Subscription Rights

We will decide all questions concerning the timeliness, validity, form and eligibility of the exercise of your subscription rights and any such determinations by us will be final and binding. We, in our sole discretion, may waive, in any particular instance, any defect or irregularity, or permit, in any particular instance, a defect or irregularity to be corrected within such time as we may determine. We will not be required to make uniform determinations in all cases. We may reject the exercise of any of your subscription rights because of any defect or irregularity. We will not accept any exercise of subscription rights until all irregularities have been waived by us or cured by you within such time as we decide, in our sole discretion. Our interpretations of the terms and conditions of the rights offering will be final and binding.

Neither we nor the subscription agent will be under any duty to notify you of any defect or irregularity in connection with your submission of subscription rights certificates, and we will not be liable for failure to notify you of any defect or irregularity. We reserve the right to reject your exercise of subscription rights if your exercise is not in accordance with the terms of the rights offering or in proper form. We will also not accept the exercise of your subscription rights if our issuance of our common shares to you could be deemed unlawful under applicable law.

No Revocation or Change

Except in the event that we make a fundamental change to the terms and conditions of the rights offering, once you submit the form of subscription rights certificate to exercise any subscription rights, you are not allowed to revoke or change the exercise or request a refund of monies paid. Except in the event that we make a fundamental change to the terms and conditions of the rights offering, all exercises of subscription rights are irrevocable, even if you learn information about us that you consider to be unfavorable. You should not exercise your subscription rights unless you are certain that you wish to purchase additional common shares at the subscription price.

Non-Transferability of the Rights

The subscription rights granted to you are non-transferable and, therefore, may not be assigned, gifted, purchased, sold or otherwise transferred to anyone else.

Rights of Subscribers

You will have no rights as a holder with respect to shares you subscribe for in the rights offering until certificates or electronic deposits representing the common shares are issued to you or your account at your broker, dealer, custodian bank or other nominee is credited with such shares. Except in the event that we make a fundamental change to the terms and conditions of the rights offering, you will have no right to revoke your subscriptions after you deliver your completed subscription rights certificate, payment in cash, as provided in this prospectus supplement, and any other required documents to the subscription agent.

Foreign Shareholders

The subscription agent will not mail this prospectus supplement or rights certificates to you if you are a shareholder whose address is outside the United States or Canada or if you have an Army Post Office or a Fleet Post Office address. Instead, we will have the subscription agent hold the subscription rights certificates for your account. To exercise your rights, you must notify the subscription agent prior to 5:00 p.m., Eastern Time, at least five business days prior to the expiration date, and establish to the satisfaction of the subscription agent that it is permitted to exercise your subscription rights under applicable law. If you do not follow these procedures by such time, your rights will expire and will have no value.

No Board Recommendations

An investment in our common shares must be made according to your evaluation of your own best interests and after considering all of the information herein, including the "Risk Factors" sections of this prospectus supplement and the accompanying prospectus. Our board of directors is making no recommendation regarding whether you should exercise your subscription rights.

Participation of Directors, Officers and Significant Shareholder

All holders of our common shares as of the record date for the rights offering will receive, at no charge, the non-transferable subscription rights to purchase our common shares as described in this prospectus supplement. To the extent that our directors and officers held our common shares as of the record date, they will receive the subscription rights and, while they are under no obligation to do so, will be entitled to participate in the rights offering. Synchron, the majority shareholder of the Company, has advised the Company that it intends to participate in the rights offering, but Synchron has not entered into any written or verbal agreement or other arrangement to do so, nor has Synchron indicated the circumstances under which it would participate in the rights offering. In the Company's December 2021 rights offering, approximately 62% of the rights were exercised by Synchron and approximately 38% of the rights were exercised by holders other than Synchron. In the Company's February 2024 rights offering, approximately 82% of the rights were exercised by Synchron and approximately 18% of the rights were exercised by holders other than Synchron. Depending on the extent to which Synchron and holders other than Synchron exercise their subscription rights in this rights offering, Synchron's ownership percentage in our outstanding common shares could be anywhere between approximately 56% and approximately 76% upon completion of the rights offering. See "Risk Factors - Regardless of the extent to which Synchron and holders other than Synchron exercise their subscription rights, Synchron will continue to hold more than 50% of our outstanding common shares after the rights offering . . . ."

Common Shares Outstanding After this Rights Offering

Based on the 516,134,712 common shares outstanding as of January 30, 2026 and the 129,033,678 common shares issuable pursuant to this rights offering, up to 645,168,390 common shares may be issued and outstanding following the rights offering, which represents an estimated increase in the number of our currently outstanding common shares of up to approximately 25%.

Fees and Expenses

Neither we nor the subscription agent will charge a brokerage commission or a fee to subscription rights holders for exercising their rights. However, if you exercise your subscription rights through a broker, dealer, custodian bank or other nominee, you will be responsible for any fees charged by your broker, dealer, custodian bank or other nominee.

Regulatory Limitation

We will not be required to issue to you our common shares pursuant to this rights offering if, in our opinion, we or you are required to obtain prior clearance or approval from any state, federal or other applicable regulatory authorities to own or control the shares and if, at the time this rights offering expires, we or you have not obtained this clearance or approval.

Questions About Exercising Subscription Rights

If you have any questions or require assistance regarding the method of exercising your subscription rights or requests for additional copies of this document or any document mentioned herein, you should contact the subscription agent at the address and telephone number set forth above under "- Delivery of Subscription Materials and Payment."

DILUTION

Purchasers of our common shares in the rights offering will experience dilution to the extent of the difference between the subscription price and our as-adjusted net tangible book value per share immediately after this rights offering. Net tangible book value per share is equal to the amount of our total tangible assets, less total liabilities, divided by the number of our outstanding common shares. As of September 30, 2025, our net tangible book value was approximately $24.7 million, or approximately $0.05 per share.

After giving effect to the sale by us in the rights offering of 129,033,678 common shares (which assumes that the rights offering is fully subscribed) at the subscription price of $0.24 per share, after deducting the estimated offering fees and expenses payable by us of $450,000, our as-adjusted net tangible book value as of September 30, 2025, would have been approximately $55.2 million, or approximately $0.09 per share. This represents an immediate increase in net tangible book value of approximately $0.04 per share to existing shareholders who do not participate in the rights offering and an immediate dilution of approximately $0.15 per share to investors purchasing our common shares in this rights offering. The following table illustrates this per share dilution (unaudited):

The information above is as of September 30, 2025 and excludes as of such date 3,705,000 outstanding stock options not otherwise exercised. To the extent that any of our outstanding stock options are exercised, or if we grant additional stock options or other awards under our stock option plan, or issue additional common shares stock in the future, there may be further dilution.

CAPITALIZATION

The following table sets forth our capitalization as of September 30, 2025 on:

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an actual basis; and

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a pro forma basis to give effect to the issuance and sale of 129,033,678 common shares in this rights offering, assuming that (i) the rights offering is fully subscribed and (ii) the net proceeds are initially held as cash and cash equivalents, pending their use as described in "Use of Proceeds."

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This table should be read in conjunction with our consolidated financial statements and the notes thereto which are incorporated by reference into this prospectus supplement.

PLAN OF DISTRIBUTION

We are distributing the subscription rights and rights certificates to individuals who own our common shares at the close of business on January 30, 2026, the record date for the rights offering. If you wish to exercise your subscription rights and purchase our common shares, you should complete the rights certificate and return it with payment for the shares to the subscription agent, Computershare Investor Services Inc., by hand delivery, overnight courier or first-class mail at the following address:

By Hand or Overnight Courier:
Computershare Investor Services Inc.
Attn: Corporate Actions
320 Bay Street, 14th Floor
Toronto, Ontario M5H 4A6
Phone Number (domestic): 1-800-564-6253

By Mail:
Computershare Investor Services Inc.
Attn: Corporate Actions
P.O. Box 7021
31 Adelaide Street East
Toronto, Ontario M5C 3H2
Phone Number (domestic): 1-800-564-6253

In the event that the rights offering is not fully subscribed, holders of rights who exercise their basic subscription privileges in full will have the opportunity to subscribe for unsubscribed common shares pursuant to the oversubscription privilege. Please see "The Rights Offering."

We have not agreed to enter into any standby or other arrangement to purchase or sell any rights or any of our securities. We have not entered into any agreements regarding stabilization activities with respect to our securities.

We have agreed to pay the subscription agent its fees plus certain expenses, which we estimate will be approximately $50,000 in the aggregate. We estimate that our total expenses in connection with the rights offering will be approximately $450,000.

Other than as described herein, we do not know of any existing agreements between any shareholder, broker, dealer, underwriter or agent relating to the sale or distribution of the common shares.

DESCRIPTION OF SECURITIES

Common Shares

For a description of our common shares, please see the section entitled "Description of Common Shares" in the accompanying prospectus.

Subscription Rights

The following is a summary description of the subscription rights being distributed to our shareholders in this rights offering. For additional information, please see "Prospectus Summary" and "The Rights Offering."

Twenty-five hundredths (or 0.25) of a subscription right per one common share. Twenty-five hundredths (or 0.25) of a subscription right will be distributed at no charge for each common share held at the close of business on the record date. There are no subscription rights outstanding as of the date of this prospectus supplement.

One new common share per whole subscription right. Each whole subscription right distributed in the rights offering entitles the holder thereof to purchase one common share at the exercise price of $0.24 per common share. There will be no changes to or adjustments in the exercise price.

Over-subscription privilege. If a subscription rights holder timely and fully exercises the basic subscription privilege with respect to all the subscription rights held and other rights holders do not exercise their subscription rights in full, a rights holder may also subscribe for an unlimited additional whole number of common shares pursuant to the over-subscription privilege, subject to availability and allocation, provided that the aggregate number of common shares issued will not exceed 129,033,678. As an illustrative example, if a holder owns 1,000 of the Company's common shares on the record date, the holder will receive subscription rights under the basic subscription privilege enabling the holder to purchase up to 250 common shares at $0.24 per share. If the holder exercises its basic subscription privilege to purchase all (but not less than all) of the 250 common shares, the holder could also exercise its oversubscription privilege to purchase additional common shares that remain unsubscribed for as a result of any other shareholders not exercising their basic subscription privilege, subject to the pro rata allocation of shares among rights holders properly exercising their oversubscription privilege.

No fractional shares. We will not issue fractional common shares in the rights offering. To the extent that the number of subscription rights that are distributed to you on the record date is not a whole number, the common shares issuable upon exercise of the basic subscription or oversubscription privilege will be rounded down to the nearest whole share for purposes of determining the number of our common shares for which you may subscribe.

Transferability. The subscription rights are not transferable.

No revocation of exercise. Except in the event that we make a fundamental change to the terms and conditions of the rights offering, all exercises of subscription rights are irrevocable.

Expiration. The subscription rights will expire at 5:00 p.m., Eastern Time, on March 4, 2026, subject to extension no later than March 6, 2026 or earlier termination. Except in the event that we make a fundamental change to the terms and conditions of the rights offering, subscription rights shall be irrevocable once they are exercised and shall continue to be irrevocable in the event the rights offering is extended.

MATERIAL UNITED STATES FEDERAL INCOME TAX CONSEQUENCES

The following discussion sets forth certain material United States federal income tax consequences to U.S. Holders (as defined below) of the receipt, exercise, disposition and expiration of the subscription rights and the ownership and disposition of our common shares received upon exercise of the subscription rights and insofar as it relates to matters of U.S. federal income tax law and regulations or legal conclusions with respect thereto, constitutes the opinion of our U.S. federal income tax counsel, Davis Graham & Stubbs LLP. This discussion is not a complete analysis or listing of all of the possible tax consequences of such transactions and does not address all tax considerations that might be relevant to particular beneficial owners of our common shares in light of their personal circumstances or to persons that are subject to special tax rules. In particular, this description of the material U.S. federal income tax consequences does not address the tax treatment of special classes of beneficial owners of our common shares, such as:

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financial institutions;

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regulated investment companies;

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real estate investment trusts;

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tax exempt entities;

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insurance companies;

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persons that do not hold our common shares as capital assets, within the meaning of Section 1221 of the Internal Revenue Code of 1986, as amended (the "Code");

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persons holding our common shares as part of an integrated or conversion transaction or a constructive sale or a straddle;

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persons that own, have owned or will own (directly, indirectly, or by attribution) 10% or more of the total combined voting power or value of our outstanding common shares;

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U.S. expatriates;

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dealers or traders in securities; or

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U.S. Holders whose functional currency is not the U.S. dollar.

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This summary does not address the alternative minimum tax, U.S. federal estate and gift tax consequences or tax consequences under any state, local or non-U.S. laws.

For purposes of this discussion, a person is a "U.S. Holder" if it is a beneficial owner of our common shares that is (1) an individual citizen or resident alien of the United States for U.S. federal income tax purposes; (2) a corporation, or other entity treated as a corporation for U.S federal income tax purposes, created or organized under the laws of the United States, any state thereof, or the District of Columbia; (3) an estate the income of which is subject to U.S. federal income taxation regardless of its source; or (4) a trust (A) if a court within the United States is able to exercise primary supervision over its administration and one or more U.S. persons have authority to control all substantial decisions of the trust or (B) that has a valid election in effect under applicable Treasury Regulations to be treated as a U.S. person.

The tax treatment of a partnership, or other pass through entity or arrangement treated as a partnership for U.S. federal income tax purposes, and each partner (or other owner) thereof will generally depend upon the status and activities of the entity and such partner (or other owner). A holder of our common shares that is treated as a partnership for U.S. federal income tax purposes should consult its own tax advisor regarding the U.S. federal income tax considerations applicable to it and its partners (or other owners).

The following discussion is based upon the Code, U.S. judicial decisions, administrative pronouncements and existing and proposed Treasury Regulations, all as in effect as of the date hereof. All of the preceding authorities are subject to change, possibly with retroactive effect, so as to result in U.S. federal income tax consequences different from those discussed below. We have not requested, and will not request, a ruling or other guidance from the U.S. Internal Revenue Service (the "IRS") with respect to any of the U.S. federal income tax consequences described below, and as a result there can be no assurance that the IRS will not disagree with or challenge any of the conclusions described herein.

This discussion is not intended to constitute a complete analysis with respect to any particular holder of all tax consequences relating to the receipt, exercise, disposition and expiration of the subscription rights and the ownership and disposition of our common shares with respect to that holder. The following discussion does not address the tax consequences of the rights offering or the related share issuance under estate, gift, foreign, state, or local tax laws. ACCORDINGLY, EACH HOLDER OF OUR COMMON SHARES SHOULD CONSULT ITS TAX ADVISOR WITH RESPECT TO THE PARTICULAR TAX CONSEQUENCES OF THE RIGHTS OFFERING AND THE RELATED SHARE ISSUANCE TO SUCH HOLDER.

THIS DISCUSSION IS PROVIDED FOR GENERAL INFORMATION ONLY AND DOES NOT CONSTITUTE LEGAL OR TAX ADVICE TO ANY U.S. HOLDER. EACH U.S. HOLDER IS ENCOURAGED TO CONSULT ITS OWN TAX ADVISORS CONCERNING THE U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE RECEIPT, EXERCISE, EXPIRATION, AND DISPOSITION OF SUBSCRIPTION RIGHTS RECEIVED IN THIS RIGHTS OFFERING IN LIGHT OF ITS PARTICULAR CIRCUMSTANCES AND ANY CONSEQUENCES ARISING UNDER THE LAWS OF ANY STATE, LOCAL, OR FOREIGN TAXING JURISDICTION.

U.S. Federal Income Tax Consequences of the Rights Offering

Receipt of Subscription Rights

Under Section 305 of the Code, a shareholder who receives a subscription right will, if such receipt is treated as a "disproportionate distribution" within the meaning of Section 305 of the Code, be treated as having received a taxable distribution in an amount equal to the value of such subscription right. In general, a shareholder who receives a subscription right will be treated as having received a "disproportionate distribution" ​(and thus a taxable distribution) if a shareholder's proportionate interest in the earnings and profits or assets of the corporation is increased and any other shareholder receives a distribution (or a deemed distribution) of cash or other property. While the issue is not free from doubt, it is the opinion of U.S. federal income tax counsel that the receipt of subscription rights by a U.S. Holder should not be treated as a "disproportionate distribution" under Section 305(b) of the Code. However, due to the uncertainties in the application of Section 305 of the Code, there can be no assurance that such treatment will not be challenged by IRS or, if challenged, upheld. If, contrary to U.S. federal income tax counsel's conclusion and corresponding opinion hereunder that the distribution of the subscription rights in this rights offering should be a non-taxable event, the distribution of subscription rights were treated as a taxable distribution, the fair market value of the subscription right a U.S. Holder receives would be taxable to such U.S. Holder as a dividend. The U.S. Holder's tax basis in such subscription right would equal the amount of the dividend and the U.S. Holder's holding period for the subscription rights would commence on the date of distribution. For further disclosure on taxation of dividends, see "Part II, Item 5. Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities - Certain U.S. Federal Income Tax Considerations - Distributions" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as filed with the SEC on March 21, 2025. The balance of the discussion below is based on U.S. federal income tax counsel's conclusion and corresponding opinion hereunder that the distribution of subscriptions rights will not be a taxable distribution.

Basis and Holding Period of Subscription Rights

A U.S. Holder's tax basis in its subscription rights will depend on the relative fair market value of the subscription rights received by such holder and the common shares owned by such holder at the time the subscription rights are distributed. If either (i) the fair market value of the subscription rights on the date such subscription rights are distributed is equal to at least 15% of the fair market value on such date of the common shares with respect to which the subscription rights are received or (ii) the U.S. Holder elects, in its United States federal income tax return for the taxable year in which the subscription rights are received, to allocate part of its tax basis in such common shares to the subscription rights, then the U.S. Holder's tax basis in the common shares with respect to which the subscription rights are received will be allocated between the common shares and the subscription rights in proportion to their respective fair market values on the date the subscription rights are distributed. If the subscription rights received by a U.S. Holder have a fair market value that is less than 15% of the fair market value of the common shares owned by such

holder at the time the subscription rights are distributed, the U.S. Holder's tax basis in its subscription rights will be zero unless the U.S. Holder elects to allocate part of its adjusted tax basis in the common shares owned by such holder to the subscription rights in the manner described in the previous sentence. The fair market value of the subscription rights on the date that the subscription rights will be distributed is uncertain, and we have not obtained, and do not intend to obtain, an appraisal of the fair market value of the subscription rights on that date. A U.S. Holder's holding period in the subscription rights will include the U.S. Holder's holding period for the common shares with respect to which the subscription rights were distributed.

Exercise of Subscription Rights

The exercise of a subscription right by, or on behalf of, a U.S. Holder will not be a taxable transaction for U.S. federal income tax purposes. The basis of each of our common shares acquired upon exercise of the subscription right will equal the sum of the subscription price and the U.S. Holder's tax basis (as determined above), if any, in the subscription right exercised. The holding period of our common shares received upon exercise of subscription rights shall begin on the day the subscription rights are exercised.

If, at the time of the receipt or exercise of the subscription right, the U.S. Holder no longer holds the common shares with respect to which the subscription right was distributed, then certain aspects of the tax treatment of the receipt and exercise of the subscription right are unclear, including (1) the allocation of the tax basis between the common shares previously sold and the subscription right received, (2) the impact of such allocation on the amount and timing of gain or loss recognized with respect to the common shares previously sold, and (3) the impact of such allocation on the tax basis of the common shares acquired upon exercise of the subscription right. U.S. Holders who exercise a subscription right received in the rights offering after disposing of our common shares with respect to which the subscription right is received, should consult their own tax advisor.

Sale or Expiration of Subscription Rights

For U.S. federal income tax purposes, gain or loss realized on a sale of subscription rights by a U.S. Holder will be capital gain or loss, and will be long-term capital gain or loss if the holding period for the subscription rights is more than one year. For these purposes, the holding period for the subscription rights will include the holding period of the common shares with respect to which the subscription rights were distributed. The deductibility of capital losses is subject to limitations. The amount of the gain or loss will be equal to the difference between the U.S. Holder's tax basis in the subscription rights disposed of (as determined above) and the amount realized on the disposition.

Gain or loss recognized by a U.S. Holder on a sale of subscription rights generally will be treated as U.S. source income or loss for U.S. foreign tax credit purposes. Consequently, the U.S. Holder may not be able to use the foreign tax credit arising from any foreign tax imposed on the disposition of a subscription right unless such credit can be applied against tax due on other income treated as derived from foreign sources in the appropriate limitation category.

In the event the subscription rights expire without being sold or exercised, the subscription rights will be deemed to have a zero basis and, therefore, the U.S. Holder will not recognize any loss upon the expiration of the subscription rights, and the U.S. Holder should re-allocate any portion of the tax basis in the U.S. Holder's common shares previously allocated to the subscription rights that have expired to their existing common shares.

U.S. Federal Income Tax Consequences of Owning and Disposing of our Common Shares Received in the Rights Offering

The U.S. federal income tax consequences of a U.S. Holder owning and disposing of our common shares that are received upon exercise of the subscription rights are described in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as filed with the SEC on March 21, 2025, under "Part II, Item 5. Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities - Certain U.S. Federal Income Tax Considerations."

CANADIAN RESALE RESTRICTIONS

The Company is a "reporting issuer" ​(within the meaning of applicable Canadian securities laws) in the applicable provinces and territories of Canada. However, the subscription rights and the common shares issuable upon exercise thereof are being distributed by the Company pursuant to an exemption from the registration and prospectus requirements in NI 45-106.

Each shareholder who directly or indirectly, alone or acting in concert with others by virtue of an agreement, arrangement, commitment or understanding, owns or controls a sufficient number of the voting rights attached to all outstanding voting securities of the Company to affect materially the control of the Company is a "control person" under applicable Canadian securities legislation, and any person who directly or indirectly, alone or acting in concert with others by virtue of an agreement, arrangement, commitment or understanding, owns or controls more than 20% of the voting rights attached to all outstanding voting securities of the Company is deemed, in the absence of evidence to the contrary, to own or control a sufficient number of the voting rights to affect materially the control of the Company.

Any sale in Canada of common shares of the Company from the holdings of a control person of the Company will be considered to be a distribution subject to the prospectus requirements of applicable Canadian securities legislation unless (i) the Company is and has been a reporting issuer in a jurisdiction of Canada for the four months immediately preceding the trade; (ii) the shareholder has held the securities for at least four months; (iii) no unusual effort is made to prepare the market or to create a demand for the security that is the subject of the trade; (iv) no extraordinary commission or consideration is paid to a person or company in respect of the trade; (v) the shareholder has no reasonable grounds to believe that the Company is in default of securities legislation; and (vi) the shareholder complies with the notice requirements set forth in section 2.8 of National Instrument 45-102 - Resale of Securities.

For any shareholder who is not a "control person" of the Company, any sale in Canada of common shares of the Company acquired upon the exercise of subscription rights under the rights offering will be considered to be a distribution subject to the prospectus requirements of applicable Canadian securities legislation unless (i) the Company is and has been a reporting issuer in a jurisdiction of Canada for the four months immediately preceding the trade; (ii) no unusual effort is made to prepare the market or to create a demand for the security that is the subject of the trade; (iii) no extraordinary commission or consideration is paid to a person or company in respect of the trade; and (iv) if the shareholder is an "insider" or "officer" of the Company within the meaning of applicable Canadian securities legislation, the shareholder has no reasonable grounds to believe that the Company is in default of securities legislation. Shareholders who are insiders of the Company may be subject to the insider reporting requirements of applicable Canadian securities legislation.

LEGAL MATTERS

The validity of the rights and common shares offered by this prospectus supplement has been passed upon for us by Fasken Martineau DuMoulin LLP, Toronto, Ontario.

Certain matters regarding the material U.S. federal income tax consequences of the rights offering have been passed upon for us by Davis Graham & Stubbs LLP, Denver, Colorado.

EXPERTS

The consolidated financial statements as of December 31, 2023 and December 31, 2024, and for the years then ended, have been incorporated by reference in this prospectus supplement and the accompanying prospectus in reliance on the report of Haynie & Company, an independent registered public accounting firm, whose report is incorporated herein by reference and given on the authority of said firm as experts in auditing and accounting.

The estimate of our mineral resources with respect to the Bear Lodge REE Project incorporated by reference in this prospectus supplement and the accompanying prospectus has been included in reliance on a technical report summary prepared by Ore Reserves Engineering, Monica Barrero Bouza and Jaye T. Pickarts.

You should rely only on the information incorporated by reference or provided in this prospectus supplement. We have authorized no one to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus supplement is accurate as of any date other than the date on the front of this prospectus supplement.

WHERE YOU CAN FIND MORE INFORMATION

We file and furnish annual, quarterly and current reports and other information, including proxy statements, with the SEC. Our SEC filings are available to the public on the SEC's website at www.sec.gov. Our SEC filings are also available through the "Investor Information" section of our website at www.rareelementresources.com.

We also file reports, statements or other information with the securities commissions or similar authorities in each of the applicable provinces and territories of Canada (the "Canadian Securities Authorities"). Copies of these documents that are filed through the System for Electronic Document Analysis and Retrieval+, or "SEDAR+," of the Canadian Securities Authorities are available on its website at www.sedarplus.ca. Documents filed on SEDAR+ are not incorporated by reference into this prospectus supplement.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to "incorporate by reference" information into this prospectus supplement, which means that we can disclose important information to you by referring you to other documents filed separately with the SEC. We incorporate by reference into this prospectus supplement the documents listed below (excluding any portions of such documents that have been "furnished" but not "filed" for purposes of the Exchange Act):

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our Annual Report on Form 10-K for the fiscal year ended December 31, 2024 filed with the SEC on March 21, 2025;

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the information in our Definitive Proxy Statement on Schedule 14A (solely those portions that were incorporated by reference into Part III of our Annual Report on Form 10-K for the year ended December 31, 2024) filed with the SEC on July 28, 2025;

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our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2025, June 30, 2025 and September 30, 2025 filed with the SEC on May 13, 2025, August 6, 2025, and November 5, 2025, respectively;

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our Current Reports on Form 8-K filed with the SEC on September 12, 2025 and January 6, 2026; and

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the description of our common shares set forth in our registration statement on Form 8-A filed on August 17, 2010, which incorporates by reference the description of our common shares set forth in our registration statement on Form 20-F filed on November 17, 2009, and any amendment or report filed for the purpose of updating such description.

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We also incorporate by reference all documents we subsequently file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the filing of this prospectus supplement and prior to the termination of the offering.

Unless specifically stated to the contrary, none of the information that we disclose under Items 2.02 or 7.01 or corresponding information furnished under Item 9.01 or included as an exhibit of any Current Report on Form 8-K that we may from time to time furnish to the SEC will be incorporated by reference into, or otherwise included in, this prospectus supplement.

We will provide without charge upon written or oral request, a copy of any or all of the documents which are incorporated by reference into this prospectus supplement. Requests should be directed to:

Rare Element Resources Ltd.
Attention: Corporate Secretary
P.O. Box 80
Firestone, Colorado 80520

Except as provided above, no other information, including information on our website, is incorporated by reference in this prospectus supplement.

PROSPECTUS

Rare Element Resouces Ltd.

$150,000,000
Senior Debt Securities
Subordinated Debt Securities
Common Shares
Warrants
Units

Rare Element Resources Ltd. (the "Company," "we," "us," or "our") may offer and sell from time to time our senior and subordinated debt securities; common shares, without par value; warrants to purchase any of the other securities that are described in this prospectus or any prospectus supplement hereto; or securities that may be convertible into or exchangeable for other securities of the Company covered hereby, or units comprised of any combination thereof, for up to an aggregate offering price of $150,000,000 million, in one or more transactions.

We will provide specific terms of any offering of securities in one or more supplements to this prospectus. The securities may be offered separately or together in any combination and as separate series. You should read this prospectus and any supplement carefully before you invest.

We may sell securities directly to you, through agents we select, or through underwriters or dealers we select. If we use agents, underwriters or dealers to sell the securities, we will name them and describe their compensation in a prospectus supplement. The net proceeds we expect to receive from an offering of securities will be described in the prospectus supplement relating to that offering.

Our common shares trade on the OTCQB Venture Marketplace under the symbol "REEMF." On April 14, 2025, the last reported sales price of our common shares on OTCQB Venture Marketplace was $1.00 per share. The applicable prospectus supplement will contain information, where applicable, as to any listing on any securities exchange of the securities covered by that prospectus supplement.

The securities offered in this prospectus involve significant risk. You should carefully consider the matters set forth in "Risk Factors" on page 9 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as filed with the Securities and Exchange Commission on March 21, 2025 and incorporated by reference, in determining whether to purchase our securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is April 15, 2025.

TABLE OF CONTENTS

As used in this prospectus, the terms the "Company," "we," "our," "ours" and "us" may, depending on the context, refer to Rare Element Resources Ltd. or its subsidiary or to Rare Element Resources Ltd. and its subsidiary, as a whole.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, which we refer to as the "SEC" or the "Commission," using a "shelf" registration process. Under the shelf registration, we may sell any combination of the securities described in this prospectus in one or more offerings. This prospectus provides you with a general description of the securities that we may offer. Each time that we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement also may add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with additional information incorporated by reference in this prospectus before making an investment in our securities. See "Where You Can Find More Information" for more information. We may use this prospectus to sell securities only if it is accompanied by a prospectus supplement.

You should not assume that the information in this prospectus, any accompanying prospectus supplement or any document incorporated by reference is accurate as of any date other than the date of such document.

WHERE YOU CAN FIND MORE INFORMATION

We file and furnish annual, quarterly and current reports and other information, including proxy statements, with the SEC. Our SEC filings are available to the public on the SEC's website at www.sec.gov. Our SEC filings are also available through the "Investor Information" section of our website at www.rareelementresources.com.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to "incorporate by reference" information into this prospectus and any accompanying prospectus supplement, which means that we can disclose important information to you by referring you to other documents filed separately with the SEC. The information incorporated by reference is considered part of this prospectus, and information filed with the SEC subsequent to this prospectus and prior to the termination of the particular offering referred to in such prospectus supplement will automatically be deemed to update and supersede this information. We incorporate by reference into this prospectus and any accompanying prospectus supplement the documents listed below (excluding any portions of such documents that have been "furnished" but not "filed" for purposes of the Exchange Act of 1934, as amended (the "Exchange Act")):

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Annual Report on Form 10-K for the fiscal year ended December 31, 2024 as filed with the SEC on March 21, 2025; and

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the description of our common shares set forth in our registration statement on Form 8-A filed on August 17, 2010, which incorporates by reference the description of our common shares set forth in our registration statement on Form 20-F filed on November 17, 2009, and any amendment or report filed for the purpose of updating such description.

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We also incorporate by reference all documents we subsequently file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the initial filing of the registration statement of which this prospectus is a part (including prior to the effectiveness of the registration statement) and prior to the termination of the offering. Any statement in a document incorporated by reference in this prospectus will be deemed to be modified or superseded to the extent a statement contained in this prospectus or any other subsequently filed document that is incorporated by reference in this prospectus modifies or supersedes such statement.

Unless specifically stated to the contrary, none of the information that we disclose under Items 2.02 or 7.01 or corresponding information furnished under Item 9.01 or included as an exhibit of any Current Report on Form 8-K that we may from time to time furnish to the SEC will be incorporated by reference into, or otherwise included in, this prospectus.

We will provide without charge upon written or oral request, a copy of any or all of the documents which are incorporated by reference into this prospectus. Requests should be directed to:

Rare Element Resources Ltd.
Attention: Corporate Secretary
P.O. Box 271049
Littleton, Colorado 80127

Except as provided above, no other information, including information on our website, is incorporated by reference in this prospectus.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements, within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Exchange Act, and forward-looking information and forward-looking statements within the meaning of applicable Canadian securities laws, with respect to our financial condition, results of operations, business prospects, plans, objectives, goals, strategies, future events, capital expenditures, and exploration and development efforts. Words such as "anticipates," "expects," "intends," "forecasts," "plans," "believes," "seeks," "estimates," "may," "will," and similar expressions (including negative and grammatical variations) tend to identify forward-looking statements.

Although we believe that our plans, intentions and expectations reflected in these forward-looking statements are reasonable, we cannot be certain that these plans, intentions or expectations will be achieved. Actual results, performance or achievements could differ materially from those contemplated, expressed or implied by the forward-looking statements contained in this prospectus.

Any statements that express or involve discussions with respect to business prospects, predictions, expectations, beliefs, plans, intentions, projections, objectives, strategies, assumptions; future events; performance or exploration and development efforts using words or phrases (including negative and grammatical variations) such as, but not limited to, "expects," "anticipates," "plans," "estimates," "intends," "forecasts," "likely," "projects," "believes," "seeks," or stating that certain actions, events or results "may," "could," "would," "should," "might" or "will" be taken, occur or be achieved, are not statements of historical fact and may be forward-looking statements. These forward-looking statements relate to, among other things:

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our business, prospects, and overall strategy;

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progress in the development of our Demonstration Plant and the timing of that progress;

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planned or estimated expenses and capital expenditures, including the Demonstration Plant's expected costs of commissioning, operation, decommissioning, and the sources of funds to pay for such costs;

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our ability to successfully manage contractors that may be under contract with another consortium member for the Demonstration Plant project, and the risk of contractor liens on the Demonstration Plant due to contractor payment disputes we do not control;

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availability of funds and capital resources;

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our Demonstration Plant team's ability to achieve the full amount of funding support from the Department of Energy ("DoE") through the remainder of the Demonstration Plant project;

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our Demonstration Plant team's ability to secure additional funding (in addition to the previously awarded funding) relating to the Demonstration Plant project or any further initiatives or advancements that may be undertaken relating to the Demonstration Plant;

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our ability to receive the remaining uncollected funds in connection with the Wyoming Energy Authority (the "WEA") grant for the Demonstration Plant;

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our ability to operate the Demonstration Plant, including in a manner to meet project objectives within the approved budget and estimated timeline;

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our estimates regarding the source, quality, costs, and timing of materials, equipment, supplies and resources, including human resources, for the commissioning, operation, and decommissioning of the Demonstration Plant;

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plans for our projects or other interests, operations, or rights;

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plans and strategies during and following the completion of operations of the Demonstration Plant, including the potential for further operation of the Demonstration Plant to meet additional objectives;

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plans and strategies relating to the advancement of the Bear Lodge REE Project;

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our plans and strategies to secure further funding for our longer-term business plans, including the advancement of the Bear Lodge REE Project through permitting and licensing, and, if feasible, ultimate construction and operations of a commercial mine and plant for processing and separation of rare earth elements;

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the timing of an amendment to the Cost Share Funding Assumption Agreement between the Company and General Atomics, whose affiliate is the Company's majority shareholder; and

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our success in obtaining, and the timing for receipts of, necessary governmental permits and approvals for our business and projects.

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Forward-looking statements are based on our current expectations and assumptions that are subject to a variety of known and unknown risks, uncertainties and other factors that could cause actual events or results to differ materially from those expressed or implied by the forward-looking statements, including, without limitation, risks associated with:

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our majority shareholder's significant influence on, or ability to control the outcome of, certain of our major corporate decisions, including our business strategies and financing options to meet our capital needs;

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our ability to protect our intellectual property rights;

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the ability of our Demonstration Plant to successfully operate and produce information that would support a decision by the Company to proceed with a potential commercial-scale production facility;

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the uncertain nature of demand for, and supply of rare earth elements, and their effect on prices for rare earth products;

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technological advancements, substitutes, and the establishment of new uses and markets for rare earth products;

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the development of new, lower cost sources of supply of rare earth products;

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development, construction and operational hazards, as well as regulatory approvals;

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our reliance on the skill and expertise of third-party service providers;

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the ability of third-party service providers to meet their contractual obligations, including as a result of supply chain disruptions and the effects those disruptions could have on our timelines and costs;

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government regulations and changes in legislation and regulations relating to the mining and rare earth industries, including environmental laws and regulations that impose material compliance costs and liabilities;

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difficulty in obtaining necessary governmental permits, licenses, and approvals for our Bear Lodge REE Project;

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governmental interventions in the mining and rare earth industries, including increases in barriers to domestic production and international trade;

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the impact of potential new and/or increased tariffs and other trade restrictions on the global trade industry;

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uncertainties regarding our ability to maintain sufficient liquidity and attract sufficient capital resources to implement our projects and strategies;

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our ability to attract and retain key personnel;

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the impact of inflation on our business, including the costs of and our ability to complete the Demonstration Plant commissioning, operations and decommissioning, and the Bear Lodge REE Project;

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the impact of external financial sector factors, including the security of our bank and investment account deposits;

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uncertainties inherent in estimates of future operating results;

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changes in competitive factors, including the development or expansion of other projects that are competitive with ours;

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China's dominance of the rare earth supply chain and its ability to significantly impact market supply, demand and prices;

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our ability to complete financings and other transactions;

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pandemics, epidemics or other disease outbreaks on supply chains and the resulting disease containment measures implemented by various governments;

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the availability and costs of goods and services we need to achieve our plans and goals resulting from military conflicts or wars such as in Russia/Ukraine and the Middle East;

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information technology system and/or data disruptions, damage, theft, failures, or cyber-attacks;

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uncertainties associated with litigation matters and opposition to our plans and operations by third parties;

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share price volatility;

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whether we deregister our common shares under the Exchange Act and/or list our common shares on a securities exchange other than the OTCQB Venture Marketplace;

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foreign and domestic government actions impacting the pricing for, or supply of, rare earth products, including changes in the actual or perceived supply and demand for rare earths due to foreign government export controls;

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the OTCQB Venture Marketplace standards and the "penny stock" rules and the impact on trading volume and liquidity due to our trading on the OTCQB Venture Marketplace;

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the consequences of Synchron, the Company's majority shareholder, discontinuing its support for the Company; and

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other factors, many of which are beyond our control.

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This list is not exhaustive of the factors that may affect our forward-looking statements. Some of the important risks and uncertainties that could affect forward-looking statements are described further under the section headings "Our Business" and "Risk Factors" in this prospectus and any additional risks or uncertainties described in any prospectus supplements. Although we have attempted to identify important factors that could cause actual results to differ materially from those described in forward-looking statements, there may be other factors that cause results not to be as anticipated, estimated or intended. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those anticipated, believed, estimated or expected. We caution readers not to place undue reliance on any such forward-looking statements, which speak only as of the date made. Except as required by law, we disclaim any obligation subsequently to revise any forward-looking statements to reflect events or circumstances after the date of such statements or to reflect the occurrence of anticipated or unanticipated events. We qualify all of the forward-looking statements contained or incorporated by reference in this prospectus by the foregoing cautionary statements.

OUR BUSINESS

We are currently focused on demonstrating the technical and economic feasibility of our proprietary processing and separation technology through the permitting and licensing, construction, and operation of a demonstration-scale processing and separation plant (the "Demonstration Plant") and advancing our Bear Lodge rare earth elements project (the "Bear Lodge REE Project") located near the town of Sundance in northeast Wyoming. The Bear Lodge REE Project consists of several large, disseminated REE deposits and a planned hydrometallurgical plant that may be located near Upton, Wyoming. The Bear Lodge REE Project is one of the highest-grade REE deposits identified in North America containing a favorable distribution of critical rare earth elements.

In our development efforts for the Bear Lodge REE Project, we have completed extensive laboratory bench-scale and pilot plant testing on metallurgical processes to recover saleable rare earth products and have been granted two patents on our metallurgical processing innovations. More specifically, we have pilot tested and received patent protection for a method for the removal of thorium from a rare earth element (REE)-containing acidic solution, as well as a method for the selective extraction of REEs from base metals in a pregnant liquid solution. In accordance with our Intellectual Property Rights Agreement with Synchron, these patented processes have been further advanced through a trade secret process alongside General Atomics, an affiliate of Synchron, the Company's majority shareholder.

Our near-term focus is on the operation of the Demonstration Plant as further described below. Assuming the Demonstration Plant operation is successful, the Company plans to evaluate the feasibility of mining through producing a separated rare earth oxide utilizing REEs from the Bear Lodge REE Project, as well as from other sources on a commercial scale.

During the first quarter of 2016, we placed the Bear Lodge REE Project under care-and-maintenance due to financial resource constraints and market conditions, and all permitting and licensing activities were suspended at that time. Based on current permitting and licensing timetables and other factors, we anticipate that once formally recommenced, we could receive all permits and licenses for the Bear Lodge REE Project approximately 36 months after resuming permitting and licensing efforts. Commencement of those efforts is dependent upon our Demonstration Plant's operating results.

If and when a decision to resume the Bear Lodge REE Project development activities is made, our plan is to advance engineering in preparation for the feasibility study, including an evaluation of a potential step approach to development beginning with a smaller initial production facility utilizing higher-grade material which could then be scaled up. Our ability to begin construction activities on the Bear Lodge REE Project will be subject to various factors, including (i) the availability of adequate capital, (ii) positive results from the Demonstration Plant's operations, (iii) an affirmative feasibility study, (iv) securing off-take agreements with customers at adequate prices, (v) obtaining necessary permits and licenses, and (vi) approval from the Company's board of directors (the "Board of Directors" or the "Board").

The Bear Lodge REE Project deposit is located near excellent mining infrastructure, including good road access and power lines within two kilometers (1.2 miles) of the Bear Lodge Property. Geographically, the Bear Lodge Property is located 100 kilometers (62.1 miles) east of Gillette, Wyoming, a major infrastructure, support, and logistics center for coal mines in the Powder River Basin that should provide for ready access to many of the required production supplies and materials as well as skilled labor. Additionally, the deposit is situated only 64 kilometers (39.8 miles) from the nearest railhead at Upton, Wyoming, where the Demonstration Plant is sited and the proposed hydrometallurgical plant may also be sited, allowing access to major distribution channels via the adjacent railhead as well as convenient access to utilities and other infrastructure.

The Company was incorporated under the laws of the Province of British Columbia, Canada on June 3, 1999 as Spartacus Capital Inc. We are currently governed under the Business Corporations Act (British Columbia) (the "BCA"). Our executive office address is P.O. Box 271049, Littleton, Colorado 80127. The telephone number for our executive office is (720) 278-2460. We maintain a corporate website at www.rareelementresources.com.

We have one direct wholly owned subsidiary, Rare Element Resources, Inc., incorporated in 1997 in the state of Wyoming, USA, formerly known as Paso Rico (USA), Inc.

Our common shares trade on the OTCQB Venture Marketplace under the symbol "REEMF."

Recent Corporate Developments

Rare Earth Demonstration Plant Project

Construction, Commissioning and Operation of the Demonstration Plant

In January 2021, a consortium of companies, of which the Company is a part, received notice from the DoE that the consortium had been selected for negotiation of a potential financial award for the engineering, construction and operation of a rare earth separation and processing Demonstration Plant. The consortium of companies is led by General Atomics, an affiliate of Synchron, the Company's majority shareholder, and includes certain of General Atomics' affiliates, the Company, and LNV, an Ardurra Group, Inc. company, as engineering and construction subcontractor. A formal proposal was submitted by the consortium in response to a published Funding Opportunity Announcement in mid-2020 for the construction and operation of a rare earth separation and processing plant utilizing the Company's proprietary technology to produce commercial-grade products. The DoE finalized the award, and an agreement was executed by the DoE's grants/agreement officer on September 27, 2021, with an effective date of October 1, 2021. The Company, as a subrecipient of the award, along with the other consortium members, commenced work on the planning and design of the Demonstration Plant project in November 2021, with the Company's contractual arrangement with General Atomics finalized in December 2021. The DoE's original funding commitment was in the amount of $21.9 million and represented approximately one-half of the originally estimated costs for the Demonstration Plant.

In September 2024, the DoE issued its final Project Continuation Notice, confirming the Demonstration Plant's readiness for operations. This notice, along with the NRC's approval of operations received in October 2024, cleared the path for operations of the Demonstration Plant to formally commence, with operations to process and separate the REE from the stockpiled mineral sample. During the operation phase, which is expected to commence in mid-2025, the Demonstration Plant is expected to produce up to 10 tons (9.1 tonnes) of NdPr oxide.

In December 2022, the Demonstration Plant achieved its final engineering design milestone, marking the DoE's first go/no-go decision point. A second go/no-go gating milestone was achieved in December 2023 with the issuance by the DoE of a Project Continuation Notice, allowing for the construction of the Demonstration Plant. In September 2024, the DoE issued its final Project Continuation Notice confirming the Demonstration Plant's readiness for operations. This notice, along with the U.S. Nuclear Regulatory Commission's (the "NRC") operations approval under its previously issued license (received in October 2024), allowed for the commencement of Demonstration Plant operations. The Company now expects to commence operations in mid-2025.

Since inception, the General Atomics-led consortium has seen increases in the Demonstration Plant project costs, including expected final equipment costs, due to, among other factors, inflation. As a result of these cost pressures, General Atomics, on behalf of the consortium, submitted to the DoE an updated Demonstration Plant construction and operations budget in 2024 of approximately $53.6 million, which is approximately 21% higher than the original budget of approximately $43.8 million. In response, the DoE pledged an additional commitment of $2.4 million (increasing its total commitment to approximately $24.3 million) in September 2024 to help fund a portion of this budget increase, with the balance to be funded by the Company, including any amounts in excess of the $53.6 million revised budget total, now estimated to be approximately $66.0 million.

Wyoming Energy Authority (WEA) Financial Award

In June 2023, the Company entered into the WEA Funding Agreement for its previously announced award of a $4.4 million grant from the WEA to be used toward the advancement of the Demonstration Plant. This award, along with funds contributed by the Company and the DoE, is being used to fund the Demonstration Plant's construction and operating costs. As of December 31, 2023, the Company had met the conditions allowing for the invoicing of $2.0 million of the $4.4 million WEA grant total. This $2.0 million was subsequently received on January 31, 2024. By September 30, 2024, the Company had met the

conditions allowing for the invoicing of an additional $2.0 million, which was subsequently received in November 2024. The remaining $400,000 of the $4.4 million grant total, which is conditioned on the achievement of other milestones, will be invoiced to the WEA once those milestones have been achieved (expected in mid-2025).

Future Funding Needs

As a result of its financing needs, the Company announced on December 5, 2023 its intention to launch a rights offering. In March 2024, the Company completed the rights offering for gross proceeds of approximately $35.8 million in which each holder of the Company's common shares as of the record date of December 15, 2023 was eligible to participate. Even with the funds raised in the rights offering and the expected receipt of the remainder of the DoE financial support and WEA grant monies, the Company will not have sufficient funds to progress certain activities, including the permitting, licensing, development, and construction related to its Bear Lodge REE Project. In the event the Company cannot secure additional financial resources or complete a strategic transaction in the longer term relating to the development of its Bear Lodge REE Project, it may need to suspend its operational plans or liquidate its business interests, and investors may lose all or part of their investment.

Current External Factors Impacting our Business

Through 2024, we continued to monitor the general U.S. political climate and actions taken by the U.S. government to secure a domestic rare earth supply chain. Due to the dominance of China over the REE supply chain, the U.S. federal government has issued several Presidential Executive Orders, under both the Biden Administration and the first and second Trump Administrations, to encourage and support the establishment of a domestic REE supply chain and to strengthen the defense industrial base with respect to critical minerals, including REEs. On January 20, 2025, President Trump issued the "Unleashing American Energy" Executive Order, which included (1) several urgent critical mineral and rare earth directives, including the immediate review of all agency actions that potentially burden the development of domestic energy resources with particular attention to critical minerals; (2) directing the Secretary of Energy to ensure that critical mineral projects, including the processing of critical minerals, receive consideration for federal support; (3) directing the Secretary of Defense to consider the needs of the U.S. in supplying and maintaining the national defense stockpile to provide a robust supply of critical minerals; and (4) establishing the U.S. position as the leading producer and processor of rare earth minerals, which will create jobs and prosperity at home, strengthen supply chains for the U.S. and its allies, and reduce the global influence of malign and adversarial states. Additionally, in early 2025, the Trump Administration announced several potential new and/or increased tariffs and other trade restrictions on exports to the United States. The impact of these trade restrictions or tariffs are unknown and could have an impact on the REE supply chain and/or the business operations.

In addition, the impacts of the COVID-19 pandemic and other external influences (such as the Russia/​Ukraine war and conflicts in the Middle East, and tariffs on certain critical mineral exports from China) have further focused the U.S. government on the importance of implementing secure domestic supply chains, including for REEs. In December 2023, China announced it had banned the export of technology to make rare earth magnets, adding to its previous export ban of critical material extraction and separation technology. In December 2024, China further banned the export of certain critical minerals, including gallium, germanium, and antimony, which have widespread military applications.

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully consider the risks set forth in the "Risk Factors" section of our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, which is incorporated in this prospectus by reference, as well as the risk factors set forth in any applicable prospectus supplement and the other reports we file from time to time with the SEC that are incorporated by reference in this prospectus. If any of the events described in such "Risk Factors" disclosures occurs or such risks otherwise materialize, our business, financial condition, results of operations, cash flows, or prospects could be materially adversely affected.

Debt securities will in most cases be unsecured debt of the Company.

The debt securities, if issued, will in most cases be unsecured debt of the Company and, in some cases, will rank equally in right of payment with all other existing and future unsecured debt of the Company. The debt securities will effectively be, in some cases, subordinated to all existing and future secured debt of the Company to the extent of the assets securing such debt. If the Company is involved in any bankruptcy, dissolution, liquidation or reorganization, the secured debt holders would, to the extent of the value of the assets securing the secured debt, be paid before the holders of unsecured debt securities, including if applicable, the debt securities. In that event, a holder of debt securities may not be able to recover any principal or interest due to it under the debt securities.

There is no existing trading market for the senior or subordinated debt securities, warrants, or units.

There is no existing trading market for the senior or subordinated debt securities, units or warrants, if issued. As a result, there can be no assurance that a liquid market will develop or be maintained for those securities, or a purchaser will be able to sell any of those securities at a particular time (if at all). The Company may not list the senior or subordinated debt securities, units or warrants on any securities exchange. The liquidity of the trading market in those securities, and the market price quoted for those securities, may be adversely affected by, among other things:

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changes in the overall market for those securities;

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changes in the financial performance or prospects of the Company;

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changes or perceived changes in our creditworthiness;

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the prospects for companies in our industry generally;

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the number of holders of those securities;

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the interest of securities dealers in making a market for those securities; and

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prevailing interest rates.

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Resales of our common shares in the public market following an offering may cause the trading price to fall.

Resales of a substantial number of our common shares could depress the trading price of our common shares. An offering of new common shares could result in resales of our common shares by our current shareholders concerned about the potential dilution of their holdings. If our shareholders sell substantial amounts of our common shares in the public market following an offering, the trading price of our common shares could fall.

If you purchase our common shares in an offering, you may experience immediate dilution.

Because the price per share of our common shares being offered may be higher than the book value per share of our common shares, you may suffer immediate and substantial dilution in the net tangible book value of our common shares you purchase in an offering. The issuance of additional common shares in future offerings could be dilutive to shareholders if they do not invest in future offerings. Moreover, to the extent that we issue options or warrants to purchase, or securities convertible into or exchangeable for, our common shares in the future and those options, warrants or other securities are exercised, converted or exchanged, shareholders may experience further dilution.

The Company's management will have certain discretion in the use of proceeds.

The Company's management will have certain discretion concerning the use of proceeds of an offering under any prospectus supplement as well as the timing of the expenditure of the proceeds thereof. As a result, investors will be relying on the judgment of management as to the specific application of the proceeds of any offering under any prospectus supplement. Management may use the net proceeds of any offering under any prospectus supplement in ways that an investor may not consider desirable. The results and effectiveness of the application of the net proceeds are uncertain.

USE OF PROCEEDS

The net proceeds to us from any offering of securities, the proposed use of those proceeds and the specific business objectives which we expect to accomplish with such proceeds will be set forth in the applicable prospectus supplement relating to that offering. Unless a prospectus supplement indicates otherwise, the net proceeds we receive from the sale of the securities offered by this prospectus will be used for general corporate purposes.

Pending the use of available funds outlined above, we intend to invest the net proceeds in an interest bearing account.

PLAN OF DISTRIBUTION

We may offer the securities directly to one or more purchasers, through agents, or through underwriters or dealers designated from time to time. We may distribute the securities from time to time in one or more transactions at a fixed price or prices (which may be changed from time to time), at market prices prevailing at the times of sale, at prices related to prevailing market prices or at negotiated prices. We may offer securities in the same offering, or we may offer securities in separate offerings. The applicable prospectus supplement will describe the terms of the offering of the securities, including:

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the offeror(s) of the securities;

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the terms of the securities to which the prospectus supplement relates;

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the name or names of any underwriters;

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the purchase price of the securities and the proceeds to be received from the sale;

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any underwriting discounts and other items constituting underwriters' compensation; and

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any discounts or concessions allowed or reallowed or paid to dealers.

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If underwriters are used in the sale, the securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The securities may be either offered to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. The obligations of the underwriters to purchase securities will be subject to the conditions precedent agreed to by the parties and the underwriters will be obligated to purchase all the securities of a class or series if any are purchased. Any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.

Underwriters or agents may make sales in privately negotiated transactions and/or any other method permitted by law, including sales deemed to be an "at-the-market" offering as defined in Rule 415 promulgated under the Securities Act and in compliance with applicable Canadian securities laws, which includes sales made directly on an existing trading market for our common shares, or sales made to or through a market maker other than on an exchange.

Securities may be sold directly by us or through agents designated by us from time to time. Any agent involved in the offer or sale of the securities in respect of which this prospectus is delivered will be named, and any commissions payable by us to any agent will be set forth, in the prospectus supplement. Unless otherwise indicated in the prospectus supplement, any agent will be acting on a best efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by eligible institutions to purchase securities from us at the public offering price set forth in the prospectus supplement under delayed delivery contracts providing for payment and delivery on a specified date in the future. The conditions to these contracts and the commissions payable for solicitation of these contracts will be set forth in the applicable prospectus supplement.

Agents and underwriters may be entitled to indemnification by us against some civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments which the agents

or underwriters may be required to make relating to these liabilities. Agents and underwriters may be customers of, engage in transactions with, or perform services for, us in the ordinary course of business.

Each class or series of securities other than the common shares will be a new issue of securities with no established trading market. Any underwriter may make a market in these securities but will not be obligated to do so and may discontinue any market making at any time without notice. There may be limited liquidity in the trading market for any such securities.

DESCRIPTION OF SENIOR AND SUBORDINATED DEBT SECURITIES

The following description, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus. While the terms we have summarized below will apply generally to any future debt securities we may offer, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. Because the terms of a specific series of debt securities may vary from the general information that we have provided below, you should rely on information in the applicable prospectus supplement that varies from any information below.

We may issue senior notes under a senior indenture to be entered into among us and a trustee to be named in the senior indenture. We may issue subordinated notes under a subordinated indenture to be entered into among us and a trustee to be named in the subordinated indenture. We have filed forms of these documents as exhibits to the registration statement which includes this prospectus. We use the term "indentures" to refer to both the senior indenture and the subordinated indenture. Unless otherwise specified in the applicable prospectus supplement, the indentures will be qualified under the Trust Indenture Act of 1939 (the "Trust Indenture Act"). We use the term "trustee" to refer to either the senior trustee or the subordinated trustee, as applicable. We urge you to read the indenture applicable to your investment; because, the indenture, and not this section, defines your rights as a holder of debt securities.

The following summaries of material provisions of senior notes, subordinated notes and the indentures are subject to, and qualified in their entirety by reference to, the provisions of the indenture applicable to a particular series of debt securities. Except as we may otherwise indicate, the terms of the senior indenture and the subordinated indenture are identical in all material respects.

General

The senior debt securities will have the same ranking as all of our other unsecured and unsubordinated debt. The subordinated debt securities will be unsecured and will be subordinated and junior to all senior indebtedness.

The debt securities may be issued in one or more separate series of senior debt securities and/or subordinated debt securities. The prospectus supplement relating to the particular series of debt securities being offered will specify the particular amounts, prices and terms of those debt securities. These terms may include:

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the title of the debt securities;

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any limit upon the aggregate principal amount of the debt securities;

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the date or dates, or the method of determining the dates, on which the debt securities will mature;

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the interest rate or rates of the debt securities, or the method of determining those rates, the interest payment dates and, for registered debt securities, the regular record dates;

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if a debt security is issued with original issue discount, the yield to maturity;

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the places where payments may be made on the debt securities;

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any mandatory or optional redemption provisions applicable to the debt securities;

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any sinking fund or analogous provisions applicable to the debt securities;

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whether and on what terms we will pay additional amounts to holders of the debt securities that are not U.S. persons in respect of any tax, assessment or governmental charge withheld or deducted and, if

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so, whether and on what terms we will have the option to redeem the debt securities rather than pay the additional amounts;

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whether the debt securities will be senior or subordinated;

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any terms for the attachment to the debt securities of warrants, options or other rights to purchase or sell our securities;

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the portion of the principal amount of the debt security payable upon the acceleration of maturity if other than the entire principal amount of the debt securities;

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any deletions of, or changes or additions to, the events of default or covenants applicable to the debt securities;

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if other than U.S. dollars, the currency or currencies in which payments of principal, premium and/or interest on the debt securities will be payable and whether the holder may elect payment to be made in a different currency;

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the method of determining the amount of any payments on the debt securities which are linked to an index;

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whether the debt securities will be issued in fully registered form without coupons;

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whether the debt securities will be issued in the form of one or more global securities in temporary or definitive form;

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whether the debt securities will be convertible into or exchangeable for common shares or other debt securities and the conversion price or exchange ratio, the conversion or exchange period and any other conversion or exchange provisions;

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any terms relating to the delivery of the debt securities if they are to be issued upon the exercise of warrants; and

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any other specific terms of the debt securities.

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Unless otherwise specified in the applicable prospectus supplement, (1) the debt securities will be registered debt securities, and (2) debt securities denominated in U.S. dollars will be issued, in the case of registered debt securities, in denominations of $1,000 or an integral multiple of $1,000. Debt securities may bear legends required by United States federal tax law and regulations.

If any of the debt securities are sold for any foreign currency or currency unit or if any payments on the debt securities are payable in any foreign currency or currency unit, the prospectus supplement will contain any restrictions, elections, tax consequences, specific terms and other information with respect to the debt securities and the foreign currency or currency unit.

Some of the debt securities may be issued as original issue discount debt securities. Original issue discount securities bear no interest during all or a part of the time that these debt securities are outstanding or bear interest at below-market rates and will be sold at a discount below their stated principal amount at maturity. The prospectus supplement will also contain any special tax, accounting or other information relating to original issue discount securities or relating to other kinds of debt securities that may be offered, including debt securities linked to an index or payable in currencies other than U.S. dollars.

Exchange, Registration and Transfer

Debt securities may be transferred or exchanged at the corporate trust office of the security registrar or at any other office or agency maintained by us or on our behalf for these purposes, without the payment of any service charge, except for any tax or governmental charges. The senior trustee initially will be the designated security registrar in the United States or Canada for the senior debt securities. The subordinated trustee initially will be the designated security registrar in the United States or Canada for the subordinated debt securities.

In the event of any redemption in part of any class or series of debt securities, we will not be required to:

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issue, register the transfer of, or exchange, debt securities of any series between the opening of business 15 days before any selection of debt securities of that series to be redeemed and the close of business on the day of mailing of the relevant notice of redemption; or

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register the transfer of, or exchange, any registered debt security selected for redemption, in whole or in part, except the unredeemed portion of any registered debt security being redeemed in part.

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Payment and Paying Agent

We will pay principal, interest and any premium on fully registered securities in the designated currency or currency unit at the office of a designated paying agent.

Global Securities

A global security represents one or any other number of individual debt securities. Generally, all debt securities represented by the same global securities will have the same terms. Each debt security issued in book-entry form will be represented by a global security that we deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, The Depository Trust Company, New York, New York, known as DTC, will be the depositary for all debt securities that are issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary or its nominee, unless special termination situations arise. As a result of these arrangements, the depositary, or its nominee, will be the sole registered holder of all debt securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account either with the depositary or with another institution that has an account with the depositary. Thus, an investor whose security is represented by a global security will not be registered holder of the debt security, but an indirect holder of a beneficial interest in the global security.

Definitive Global Securities

Book-Entry Securities. Debt securities of a series represented by a definitive global registered debt security and deposited with or on behalf of a depositary in the United States will be represented by a definitive global debt security registered in the name of the depositary or its nominee. Upon the issuance of a global debt security and the deposit of the global debt security with the depositary, the depositary will credit, on its book-entry registration and transfer system, the respective principal amounts represented by that global debt security to the accounts of participating institutions that have accounts with the depositary or its nominee. The accounts to be credited shall be designated by the underwriters or agents for the sale of book-entry debt securities or by us, if these debt securities are offered and sold directly by us.

Ownership of book-entry debt securities will be limited to participants or persons that may hold interests through participants. In addition, ownership of book-entry debt securities will be evidenced only by, and the transfer of that ownership will be effected only through, records maintained by the depositary or its nominee for the definitive global debt security or by participants or persons that hold through participants.

So long as the depositary or its nominee is the registered owner of a global debt security, that depositary or nominee, as the case may be, will be considered the sole owner or holder of the book-entry debt securities represented by that global debt security for all purposes under the indenture. Payment of principal of, and premium and interest, if any, on, book-entry debt securities will be made to the depositary or its nominee as the registered owner or the holder of the global debt security representing the book-entry debt securities. Owners of book-entry debt securities:

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will not be entitled to have the debt securities registered in their names;

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will not be entitled to receive physical delivery of the debt securities in definitive form; and

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will not be considered the owners or holders of the debt securities under the indenture.

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The laws of some jurisdictions require that purchasers of securities take physical delivery of securities in definitive form. These laws impair the ability to purchase or transfer book-entry debt securities.

We expect that the depositary for book-entry debt securities of a series, upon receipt of any payment of principal of, or premium or interest, if any, on, the related definitive global debt security, will immediately credit participants' accounts with payments in amounts proportionate to their respective beneficial interests in the principal amount of the global debt security as shown on the records of the depositary. We also expect that payments by participants to owners of beneficial interests in a global debt security held through those participants will be governed by standing instructions and customary practices and will be the responsibility of those participants.

Consolidation, Merger, Sale or Conveyance

We may, without the consent of the holders of the debt securities, merge into or consolidate with any other person, or convey or transfer all or substantially all of our properties and assets to another person provided that the successor assumes on the same terms and conditions all the obligations under the debt securities and the indentures.

The remaining or acquiring person will be substituted for us in the indentures with the same effect as if it had been an original party to the indenture. A prospectus supplement will describe any other limitations on our ability to merge into, consolidate with, or convey or transfer all or substantially all of our properties and assets to, another person.

Satisfaction and Discharge; Defeasance

We may be discharged from our obligations on the debt securities of any class or series that have matured or will mature or be redeemed within one year if we deposit with the trustee enough cash and/or U.S. government obligations to pay all the principal, interest and any premium due to the stated maturity or redemption date of the debt securities and comply with the other conditions set forth in the applicable indenture, which will described in the applicable prospectus supplement. The principal conditions that we must satisfy to discharge our obligations on any debt securities are (1) pay all other sums payable with respect to the applicable series of debt securities and (2) deliver to the trustee an officers' certificate and an opinion of counsel that state that the required conditions have been satisfied.

Each indenture contains a provision that permits us to elect to be discharged from all of our obligations with respect to any class or series of debt securities then outstanding. However, even if we affect a legal defeasance, some of our obligations will continue, including obligations to:

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maintain and apply money in the defeasance trust,

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register the transfer or exchange of the debt securities,

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replace mutilated, destroyed, lost or stolen debt securities, and

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maintain a registrar and paying agent in respect of the debt securities.

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The indentures specify the types of U.S. government obligations that we may deposit, which will be described in the applicable prospectus supplement.

Events of Default, Notice and Waiver

Except as may be set forth in the applicable prospectus supplement, each indenture defines an event of default with respect to any class or series of debt securities as one or more of the following events:

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failure to pay interest on any debt security of the class or series for 90 days when due;

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failure to pay the principal or any premium on any debt securities of the class or series when due;

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failure to make any sinking fund payment when due;

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failure to perform any other covenant in the debt securities of the series or in the applicable indenture with respect to debt securities of the series for 90 days after being given notice; and

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occurrence of an event of bankruptcy, insolvency or reorganization set forth in the indenture.

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An event of default for a particular class or series of debt securities does not necessarily constitute an event of default for any other class or series of debt securities issued under an indenture.

If any event of default as to a series of debt securities occurs and is continuing, the trustee or the holders of at least 25% in principal amount of the then outstanding debt securities of that series may declare all the debt securities to be due and payable immediately.

The holders of a majority in aggregate principal amount of the debt securities of that series then outstanding by notice to the trustee may on behalf of the holders of all of the debt securities of that series waive any existing default or event of default and its consequences under the applicable indenture except a continuing default or event of default in the payment of interest on, or the principal of, the debt securities of that series.

Each indenture requires the trustee to, within 90 days after the occurrence of a default known to it with respect to any outstanding series of debt securities, give the holders of that class or series notice of the default if uncured or not waived. However, the trustee may withhold this notice if it determines in good faith that the withholding of this notice is in the interest of those holders, except that the trustee may not withhold this notice in the case of a payment default. The term "default" for the purpose of this provision means any event that is, or after notice or lapse of time or both would become, an event of default with respect to debt securities of that series.

Other than the duty to act with the required standard of care during an event of default, a trustee is not obligated to exercise any of its rights or powers under the applicable indenture at the request or direction of any of the holders of debt securities, unless the holders have offered to the trustee reasonable security and indemnity. Each indenture provides that the holders of a majority in principal amount of outstanding debt securities of any series may direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or other power conferred on the trustee if the direction would not conflict with any rule of law or with the indenture. However, the trustee may take any other action that it deems proper which is not inconsistent with any direction and may decline to follow any direction if it in good faith determines that the directed action would involve it in personal liability.

Each indenture includes a covenant that we will file annually with the trustee a certificate of no default, or specifying any default that exists.

Modification of the Indentures

We and the applicable trustee may modify an indenture without the consent of the holders for limited purposes, including adding to our covenants or events of default, establishing forms or terms of debt securities, curing ambiguities and other purposes which do not adversely affect the holders of debt securities, considered as a group, in any material respect.

We and the applicable trustee may make modifications and amendments to an indenture with the consent of the holders of a majority in principal amount of the outstanding debt securities of all affected series. However, without the consent of each affected holder, no modification may:

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change the stated maturity of any debt security;

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reduce the principal, premium, if any, or rate of interest on any debt security; or

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reduce the percentage of holders of outstanding debt securities of any series required to consent to any modification, amendment or waiver under the indenture.

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Notices

Notice to holders of registered debt securities will be given by mail to the addresses of those holders as they appear in the security register.

Replacement of Securities Coupons

Debt securities or coupons that have been mutilated will be replaced by us at the expense of the holder upon surrender of the mutilated debt security or coupon to the security registrar. Debt securities or coupons that become destroyed, stolen, or lost will be replaced by us at the expense of the holder upon delivery to the security registrar of evidence of its destruction, loss, or theft satisfactory to us and the security registrar. In the case of a destroyed, lost, or stolen debt security or coupon, the holder of the debt security or coupon may be required to provide reasonable security or indemnity to the trustee and us before a replacement debt security will be issued.

Concerning the Trustees

We may from time to time maintain lines of credit, and have other customary banking relationships, with any of the trustees.

Senior Debt Securities

The senior debt securities will rank equally with all of our other unsecured and non-subordinated debt.

Certain Covenants in the Senior Indenture

The prospectus supplement relating to a series of senior debt securities will describe any material covenants in respect of that series of senior debt securities.

Subordinated Debt Securities

The subordinated debt securities will be unsecured. The subordinated debt securities will be subordinate in right of payment to all senior indebtedness. In addition, claims of creditors generally will have priority with respect to the assets and earnings of our subsidiary over the claims of our creditors, including holders of the subordinated debt securities, even though those obligations may not constitute senior indebtedness. The subordinated debt securities, therefore, will be effectively subordinated to creditors, including trade creditors, with regard to the assets of our subsidiary. Creditors of our subsidiary may include trade creditors, secured creditors and creditors holding guarantees issued by our subsidiary.

Unless otherwise specified in a prospectus supplement, senior indebtedness shall mean the principal of, premium, if any, and interest on, all indebtedness for money borrowed by us and any deferrals, renewals, or extensions of any senior indebtedness. Indebtedness for money borrowed by us includes all indebtedness of another person for money borrowed that we guarantee, other than the subordinated debt securities, whether outstanding on the date of execution of the subordinated indenture or created, assumed or incurred after the date of the subordinated indenture. However, senior indebtedness will not include any indebtedness that expressly states to have the same rank as the subordinated debt securities or to rank junior to the subordinated debt securities. Senior indebtedness will also not include any of our obligations to our subsidiary.

The senior debt securities constitute senior indebtedness under the subordinated indenture. A prospectus supplement will describe the relative ranking among different series of subordinated debt securities.

Unless otherwise specified in a prospectus supplement, we may not make any payment on the subordinated debt securities and may not purchase, redeem, or retire any subordinated debt securities if any senior indebtedness is not paid when due or the maturity of any senior indebtedness is accelerated as a result of a default, unless the default has been cured or waived, and the acceleration has been rescinded, or the senior indebtedness has been paid in full. We may, however, pay the subordinated debt securities without regard to these limitations if we or the subordinated trustee receive written notice approving the payment from the representatives of the holders of senior indebtedness with respect to which either of the events set forth above has occurred and is continuing. Unless otherwise specified in a prospectus supplement, during the continuance of any default with respect to any designated senior indebtedness under which its maturity may be accelerated immediately without further notice or the expiration of any applicable grace periods, we may not pay the subordinated debt securities for 90 days after the receipt by the subordinated trustee of written notice of a default from the representatives of the holders of designated senior indebtedness. If the

holders of designated senior indebtedness or the representatives of those holders have not accelerated the maturity of the designated senior indebtedness at the end of the 90-day period, we may resume payments on the subordinated debt securities. Only one notice may be given in any consecutive 360-day period, irrespective of the number of defaults with respect to designated senior indebtedness during that period.

In the event that we pay or distribute our assets to creditors upon a total or partial liquidation, dissolution or reorganization of our company or our property, the holders of senior indebtedness will be entitled to receive payment in full of the senior indebtedness before the holders of subordinated debt securities are entitled to receive any payment. Until the senior indebtedness is paid in full, any payment or distribution to which holders of subordinated debt securities would be entitled but for the subordination provisions of the subordinated indenture will be made to holders of the senior indebtedness as their interests may appear. However, holders of subordinated debt securities will be permitted to receive distributions of shares and debt securities subordinated to the senior indebtedness. If a distribution is made to holders of subordinated debt securities that, due to the subordination provisions, should not have been made to them, the holders of subordinated debt securities are required to hold it in trust for the holders of senior indebtedness, and pay it over to them as their interests may appear.

If payment of the subordinated debt securities is accelerated because of an event of default, either we or the subordinated trustee will promptly notify the holders of senior indebtedness or the representatives of the holders of the acceleration. We may not pay the subordinated debt securities until five business days after the holders or the representatives of the senior indebtedness receive notice of the acceleration. Afterwards, we may pay the subordinated debt securities only if the subordination provisions of the subordinated indenture otherwise permit payment at that time.

As a result of the subordination provisions contained in the subordinated indenture, in the event of insolvency, our creditors who are holders of senior indebtedness may recover more, ratably, than the holders of subordinated debt securities. In addition, our creditors who are not holders of senior indebtedness may recover less, ratably, than holders of senior indebtedness and may recover more, ratably, than the holders of subordinated indebtedness.

The prospectus supplement relating to a series of subordinated debt securities will describe any material covenants in respect of any series of subordinated debt securities.

Conversion or Exchange

We may issue debt securities that we may convert or exchange into common shares or other securities, property or assets. If so, we will describe the specific terms on which the debt securities may be converted or exchanged in the applicable prospectus supplement. The conversion or exchange may be mandatory, at your option, or at our option. The applicable prospectus supplement will describe the manner in which the shares of common shares or other securities, property or assets you would receive would be issued or delivered.

DESCRIPTION OF COMMON SHARES

We are authorized to issue an unlimited number of common shares, without par value. As of April 4, 2025, we had 516,134,712 common shares issued and outstanding. All common shares are of the same class and, once issued, rank equally as to dividends, voting powers, and participation in assets.

Dividend Rights

Holders of common shares are entitled to receive such dividends as may be declared from time to time by our board of directors, in its discretion, out of funds legally available therefor.

Voting Rights

Holders of common shares are entitled to one vote for each share held of record on all matters to be acted upon by the shareholders.

Election of Directors

In accordance with the BCA, directors are elected by a plurality of the votes cast by the holders of our common shares in a meeting at which a quorum is present. "Plurality" means that the individuals who receive the largest number of votes cast are elected as directors, up to the maximum number of directors to be chosen at the meeting.

Liquidation

Upon liquidation, dissolution or winding up of the Company, holders of common shares are entitled to receive pro rata the assets of the Company, if any, remaining after payments of all debts and liabilities.

Redemption

No shares have been issued subject to call or assessment. There are no pre-emptive or conversion rights and no provisions for redemption or purchase for cancellation, surrender, or sinking or purchase funds.

Other Provisions

Changes to Authorized Share Structure

Under Article 9 of the Company's Articles, and subject to the BCA, the Company may by ordinary resolution of the shareholders:

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create one or more classes or series of shares or, if none of the shares of a series of a class or series of shares are allotted or issued, eliminate that class or series of shares;

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increase, reduce or eliminate the maximum number of shares that the Company is authorized to issue out of any class or series of shares or establish a maximum number of shares that the Company is authorized to issue out of any class or series of shares for which no maximum is established;

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if the Company is authorized to issue shares of a class or shares with par value:

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decrease the par value of those shares; or

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if none of the shares of that class of shares are allotted or issued, increase the par value of those shares;

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alter the identifying name of any of its shares; or

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otherwise alter its share or authorized share structure when required or permitted to do so by the BCA.

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Subject to Article 9.2 of the Company's Articles and the BCA, the Company may by ordinary resolution of the shareholders:

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create special rights or restrictions for, and attach those special rights or restrictions to, the shares of any class or series of shares, whether or not any or all of those shares have been issued;

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vary or delete any special rights or restrictions attached to the shares of any class or series of shares, whether or not any or all of those shares have been issued; or

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change all or any of its unissued, or fully paid issued, shares with par value into shares without par value or any of its unissued shares without par value into shares with par value.

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Subject to Article 9.2 of the Company's Articles and the BCA, the Company may by resolution of the directors subdivide or consolidate all or any of its unissued, or fully paid issued, shares.

General

You should read the prospectus supplement relating to any offering of common shares, or of securities convertible, exchangeable or exercisable for common shares, for the terms of the offering, including the number of common shares offered, any initial offering price and market prices relating to the common shares.

This section is a summary and may not describe every aspect of our common shares that may be important to you. We urge you to read applicable British Columbia law and our Articles, because they, and not this description, define your rights as a holder of our common shares. See "Where You Can Find More Information" for information on how to obtain copies of these documents.

DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of debt securities, common shares or other securities. Warrants may be issued independently or together with debt securities, common shares or other securities offered by any prospectus supplement and may be attached to or separate from any such offered securities. Series of warrants may be issued under a separate warrant agreement entered into between us and a bank or trust company, as warrant agent, as will be set forth in the prospectus supplement relating to the particular issue of warrants. The warrant agent would act solely as our agent in connection with the warrants and would not assume any obligation or relationship of agency or trust for or with any holders of warrants or beneficial owners of warrants.

You should refer to the provisions of the warrant agreement that will be filed with the SEC and any other applicable securities commissions or similar regulatory authorities in connection with the offering of warrants for the complete terms of the warrant agreement.

Prior to the exercise of any warrants, holders of such warrants will not have any rights of holders of the securities purchasable upon such exercise, including the right to receive payments of dividends or the right to vote such underlying securities.

DESCRIPTION OF UNITS

As specified in the applicable prospectus supplement, we may issue units consisting of one or more debt securities, common shares, warrants or any combination of such securities. In addition, the prospectus supplement relating to units will describe the terms of any units we issue, including as applicable:

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the designation and terms of the units and the securities included in the units;

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any provision for the issuance, payment, settlement, transfer or exchange of the units;

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the date, if any, on and after which the units may be transferable separately;

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whether we will apply to have the units traded on a securities exchange or securities quotation system;

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any material Canadian and/or United States federal income tax consequences; and

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how, for Canadian and/or United States federal income tax purposes, the purchase price paid for the units is to be allocated among the component securities.

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LEGAL MATTERS

Fasken Martineau DuMoulin LLP of Toronto, Ontario, Canada has provided its opinion on the validity of the securities offered by this prospectus.

EXPERTS

The consolidated financial statements as of December 31, 2023, and December 31, 2024, and for the years then ended have been incorporated by reference in this prospectus and registration statement in reliance on the report of Haynie & Company, an independent registered public accounting firm, whose report is incorporated herein by reference and given on the authority of said firm as experts in auditing and accounting.

The estimate of our mineral resources with respect to the Bear Lodge REE Project incorporated by reference in this prospectus has been included in reliance on a technical report summary prepared by Ore Reserves Engineering, Monica Barrero Bouza and Jaye T. Pickarts.

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Subscription Rights to Purchase an Aggregate of up to 129,033,678 Common Shares of Rare Element Resources Ltd.

Up to 129,033,678 Common Shares of Rare Element Resources Ltd. Issuable Upon the Exercise of Subscription Rights

PROSPECTUS SUPPLEMENT

February 6, 2026

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