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NATURE OF OPERATIONS (Details) - USD ($) $ in Thousands |  |  | 12 Months Ended
--- | --- | --- | ---
Mar. 10, 2021 | May 23, 2019 | Dec. 31, 2020 | Dec. 31, 2018
Ownership interests in various mines |  |  | 100.00% |
Ownership interest (as a percent) |  |  | 49.00% |
Proceeds in connection with the equity issuance |  | $ 2,600 |  | $ 918
Equity Issuances | Subsequent Events |  |  |  |
Proceeds in connection with the equity issuance | $ 64,400 |  |  |
MSC | Equity Method Investment |  |  |  |
Ownership interest (as a percent) |  |  | 49.00% |

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