Revenues - Disaggregation of revenue (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($) oz	Sep. 30, 2021 USD ($) oz	Sep. 30, 2022 USD ($) oz	Sep. 30, 2021 USD ($) oz
Disaggregation of Revenue [Line Items]
Revenues	$ 8,758	$ 31,676	$ 21,755	$ 86,713
Customer concentration risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage	100.00%	100.00%	100.00%	100.00%
Customers A
Disaggregation of Revenue [Line Items]
Revenues	$ 8,665	$ 4,284	$ 11,163	$ 7,945
Customers A | Customer concentration risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage	98.90%	13.50%	51.30%	9.20%
Customer B
Disaggregation of Revenue [Line Items]
Revenues	$ 93	$ 27,392	$ 10,592	$ 78,337
Customer B | Customer concentration risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage	1.10%	86.50%	48.70%	90.30%
Customer C
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 431
Customer C | Customer concentration risk | Revenue
Disaggregation of Revenue [Line Items]
Percentage	0.00%	0.00%	0.00%	0.50%
Gold sales
Disaggregation of Revenue [Line Items]
Revenues	$ 8,456	$ 29,129	$ 21,057	$ 77,570
Ounces Sold | oz	4,817	16,354	11,557	43,244
Silver sales
Disaggregation of Revenue [Line Items]
Revenues	$ 302	$ 2,547	$ 698	$ 9,143
Ounces Sold | oz	15,131	105,478	32,010	352,480