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Long-term Reclamation Liability and Retirement Obligation Asset (Reconciliation of Aggregate Retirement Liability) (Details) - USD ($)
12 Months Ended
Apr. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Long-term reclamation liability — beginning of year   $ 7,441,091 $ 7,417,680
Reduction of obligation $ (400,000) (410,018) 0
Amount reclassified to liabilities held for sale   (1,019,705) 0
Accretion of reclamation liability   22,840 23,411
Long-term reclamation liability — end of year   $ 6,034,208 $ 7,441,091