CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenues - Note 13	$ 31,676,000	$ 12,291,000	$ 86,713,000	$ 31,051,000
Cost of sales:
Production costs	30,616,000	10,865,000	77,927,000	27,286,000
Depreciation and amortization	1,577,000	675,000	4,191,000	1,999,000
Mine site period costs - Note 4	11,467,000	14,230,000	24,445,000	34,292,000
Write-down of production inventories - Note 4	0	0	0	17,924,000
Total cost of sales	43,660,000	25,770,000	106,563,000	81,501,000
Operating expenses:
General and administrative	3,313,000	5,711,000	12,271,000	18,149,000
Projects and development	2,344,000	0	3,860,000	0
Write-off of deposit	916,000	0	916,000	0
Accretion - Note 12	102,000	93,000	306,000	280,000
Impairment on equipment not in use - Note 5	0	5,331,000	0	5,331,000
Loss from operations	(18,659,000)	(24,614,000)	(37,203,000)	(74,210,000)
Other (expense) income:
Interest expense, net of capitalized interest - Note 9	(5,461,000)	(4,319,000)	(15,176,000)	(39,278,000)
Fair value adjustment to warrants - Notes 11 and 18	812,000	(3,354,000)	10,956,000	(4,276,000)
Interest income	0	9,000	0	156,000
Loss before income taxes	(23,308,000)	(32,278,000)	(41,423,000)	(117,608,000)
Income tax benefit - Note 15	95,000	0	95,000	0
Net loss	$ (23,213,000)	$ (32,278,000)	$ (41,328,000)	$ (117,608,000)
Earnings Per Share [Abstract]
Basic (in dollars per share)	$ (0.39)	$ (0.64)	$ (0.69)	$ (5.10)
Diluted (in dollars per share)	$ (0.39)	$ (0.64)	$ (0.69)	$ (5.10)
Weighted average shares outstanding:
Basic (in shares)	60,114,358	50,160,080	59,989,457	23,059,068
Diluted (in shares)	60,114,358	50,160,080	59,989,457	23,059,068