Mineral interests include acquired interests in exploration stage properties, including the costs of options to acquire such properties. Exploration costs are expensed as incurred. Costs of rights or options to explore and lease properties are considered exploration costs and expensed as incurred. As of September 30, 2026, the mineral interests capitalized are held by FRE Australia, whereas the costs of arrangements entered into by AMBPL have been expensed as incurred. In the event that the Company exercises its options under one or more option agreements and begins commercial exploration, it will be required to make royalty payments based on a percentage of production revenue as defined in the agreements.

In connection with the Company’s Mineral Rights Assignment and Covenants Agreement (the “Greenfield Agreement”), and following the completion of the Offering, the Company issued 19,052 shares of its common stock to Greenfield Exploration Ltda. and Focus Capital Partners Pty Ltd. The issuance represents equity consideration in lieu of cash for a portion of the contractual payment obligations triggered by the Offering, consistent with the terms of the Greenfield Agreement.

On July 31, 2026, Foothills Rare Earths, LLC ("FRE US") exercised its option under a Third Amendment to the Option and Project Evaluation Agreement with SEM and its members to acquire and assume the Mining Lease Agreement dated October 1, 2020 between SEM and Weyerhaeuser Company, as amended (the "Weyerhaeuser Lease"). On August 20, 2026, SEM assigned the Weyerhaeuser Lease to FRE US for consideration of $375 in cash and 165,153 shares of the Company's common stock issued in a private placement exempt from registration under the Securities Act of 1933, as amended.

On June 30, 2026, the Company, through its subsidiary AMBPL, delivered notice of exercise of its option to acquire certain mining rights in Brazil (the "GMC Option"), as described in the Prospectus. The exercise price was payable solely in shares of the Company's common stock, determined using the $19.00 initial public offering price. Prior to settlement, the area of one of the underlying exploration applications was reduced, which proportionately reduced the exercise price and the number of shares issuable from the 271,579 shares previously disclosed. In September 2026, following execution of definitive subscription agreements, the Company issued 262,086 shares of common stock in settlement of the exercise price. The total value of the option exercise was $4,979 which was expensed to exploration and evaluation expenses in the condensed consolidated statement of operations for the three and nine months ended September 30, 2026.

Weyerhaeuser Lease

On August 20, 2026, FRE US acquired the Weyerhaeuser Lease through an assignment from SEM. The Weyerhaeuser Lease is a mining lease effective October 1, 2020, located in Harris and Talbot Counties, Georgia. It provides for annual rental payments of $75, subject to annual inflation adjustment, which began in the fourth lease year commencing October 1, 2023, and a 5% royalty on rare earth products and byproducts produced from the lease area.