Property, Plant and Equipment, Net - Components of plant and equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	$ 86,828		$ 86,554
Less, accumulated depreciation and amortization	(32,447)		(31,722)
Total	54,381		54,832
Payments to acquire mineral properties	271	$ 351
Production leach pads
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	$ 11,190		11,190
Test leach pads
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	18 months
Plant, equipment and mine development, gross	$ 6,241		6,241
Process equipment
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	$ 17,302		17,302
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	10 years
Plant, equipment and mine development, gross	$ 9,342		9,280
Mine equipment
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	4,975		4,872
Vehicles
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	$ 1,578		1,578
Furniture and office equipment
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	7 years
Plant, equipment and mine development, gross	$ 370		370
Mineral properties(1)
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	50		0
Payments to acquire mineral properties	50
Construction in progress and other
Property, Plant and Equipment [Line Items]
Plant, equipment and mine development, gross	$ 35,780		$ 35,721
Minimum | Process equipment
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	5 years
Minimum | Mine equipment
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	5 years
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	3 years
Maximum | Process equipment
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	15 years
Maximum | Mine equipment
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	7 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
Depreciation Life or Method	5 years