ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS	6 Months Ended
Jun. 30, 2026
Asset Retirement Obligation Disclosure [Abstract]
ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS	ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS Asset Retirement Obligations The Company estimates asset retirement obligations based on the requirements to reclaim certain land areas associated with mineral extraction activities and certain related facilities at Mountain Pass. Minor reclamation activities related to discrete portions of the Company’s operations are ongoing. As of June 30, 2026, the Company estimated a significant portion of the cash outflows for major reclamation activities, including the retirement of Mountain Pass, will be incurred beginning in 2053. As of June 30, 2026, the credit-adjusted risk-free rate ranged between 6.5% and 8.8% depending on the timing of expected settlement and when the increment was recognized. There were no significant increments or decrements for the three and six months ended June 30, 2026 and 2025. The non-current portions of the Company’s asset retirement obligations, which are included in “Other non-current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were $8.0 million and $7.7 million as of June 30, 2026, and December 31, 2025, respectively. The current portions, which are included in “Other current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were not material. The total estimated future undiscounted cash flows required to satisfy the Company’s asset retirement obligations were $51.3 million and $51.4 million as of June 30, 2026, and December 31, 2025, respectively. Environmental Obligations The Company has certain environmental monitoring and remediation obligations related to the groundwater contamination in and around Mountain Pass. As of June 30, 2026, the Company estimated the cash outflows related to these environmental activities will be incurred annually over the next 30 years but could be longer. The Company’s environmental obligations are measured at the expected value of future cash outflows discounted to their present value using a discount rate of 4.84%. There were no significant changes in the estimated remaining costs for the three and six months ended June 30, 2026 and 2025. The total estimated aggregate undiscounted cost of $39.9 million and $40.3 million as of June 30, 2026, and December 31, 2025, respectively, principally related to groundwater monitoring and remediation activities required by state and local agencies. Based on the Company’s estimate of the cost, timing and the assumption that payments are considered to be fixed and reliably determinable, the Company has discounted the liability. The non-current portions of the Company’s environmental obligations, which are included in “Other non-current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were $18.4 million as of both June 30, 2026, and December 31, 2025. The current portions, which are included in “Other current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were not material. Financial Assurances The Company is required to provide certain government agencies with financial assurances relating to closure and reclamation obligations. As of both June 30, 2026, and December 31, 2025, the Company had financial assurance requirements of $46.2 million, which were satisfied with surety bonds placed with applicable California state and regional agencies.

The Company estimates asset retirement obligations based on the requirements to reclaim certain land areas associated with mineral extraction activities and certain related facilities at Mountain Pass. Minor reclamation activities related to discrete portions of the Company’s operations are ongoing. As of June 30, 2026, the Company estimated a significant portion of the cash outflows for major reclamation activities, including the retirement of Mountain Pass, will be incurred beginning in 2053.

As of June 30, 2026, the credit-adjusted risk-free rate ranged between 6.5% and 8.8% depending on the timing of expected settlement and when the increment was recognized. There were no significant increments or decrements for the three and six months ended June 30, 2026 and 2025.

The non-current portions of the Company’s asset retirement obligations, which are included in “Other non-current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were $8.0 million and $7.7 million as of June 30, 2026, and December 31, 2025, respectively. The current portions, which are included in “Other current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were not material. The total estimated future undiscounted cash flows required to satisfy the Company’s asset retirement obligations were $51.3 million and $51.4 million as of June 30, 2026, and December 31, 2025, respectively.

The Company has certain environmental monitoring and remediation obligations related to the groundwater contamination in and around Mountain Pass. As of June 30, 2026, the Company estimated the cash outflows related to these environmental activities will be incurred annually over the next 30 years but could be longer. The Company’s environmental obligations are measured at the expected value of future cash outflows discounted to their present value using a discount rate of 4.84%. There were no significant changes in the estimated remaining costs for the three and six months ended June 30, 2026 and 2025.

The total estimated aggregate undiscounted cost of $39.9 million and $40.3 million as of June 30, 2026, and December 31, 2025, respectively, principally related to groundwater monitoring and remediation activities required by state and local agencies. Based on the Company’s estimate of the cost, timing and the assumption that payments are considered to be fixed and reliably determinable, the Company has discounted the liability. The non-current portions of the Company’s environmental obligations, which are included in “Other non-current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were $18.4 million as of both June 30, 2026, and December 31, 2025. The current portions, which are included in “Other current liabilities” within the Company’s unaudited Condensed Consolidated Balance Sheets, were not material.

The Company is required to provide certain government agencies with financial assurances relating to closure and reclamation obligations. As of both June 30, 2026, and December 31, 2025, the Company had financial assurance requirements of $46.2 million, which were satisfied with surety bonds placed with applicable California state and regional agencies.