ASSET RETIREMENT OBLIGATIONS - Reclamation and Accretion (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclamation obligations
Reclamation adjustment reflecting updated estimates	$ 830	$ 411	$ 1,256	$ 614
Reclamation accretion	479	475	1,470	1,389
Total	$ 1,309	$ 886	$ 2,725	$ 2,003

Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values. Excludes accretion associated with asset retirement obligations.

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