Revenues - Disaggregation of revenue (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) oz	Sep. 30, 2020 USD ($) oz	Sep. 30, 2021 USD ($) oz	Sep. 30, 2020 USD ($) oz
Disaggregation of Revenue [Line Items]
Revenues	$ 31,676	$ 12,291	$ 86,713	$ 31,051
Gold sales
Disaggregation of Revenue [Line Items]
Revenues	$ 29,129	$ 11,623	$ 77,570	$ 29,234
Ounces Sold | oz	16,354	6,056	43,244	16,854
Silver sales
Disaggregation of Revenue [Line Items]
Revenues	$ 2,547	$ 668	$ 9,143	$ 1,817
Ounces Sold | oz	105,478	27,251	352,480	97,954