Segment Reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Number of geographic regions | segment			3
Balance sheet information
Total current assets	$ 21,972		$ 21,972			$ 26,495
Total non-current assets	133,474		133,474			157,391
Total assets	155,446		155,446			183,886
Total current liabilities	15,879		15,879			11,325
Total non-current liabilities	82,258		82,258			75,868
Total shareholders' equity	57,309	$ 99,514	57,309	$ 99,514	$ 67,021	96,693	$ 106,701	$ 111,764
Total liabilities and shareholders' equity	155,446		155,446			183,886
Income statement information
Sales, net	13,272	20,552	52,756	76,587
Total mine cost of sales, including depreciation	21,942	24,963	67,187	79,238
Exploration expense	969	1,960	2,399	5,239
Total other costs and expenses, including G&A	4,473	3,629	14,468	9,736
Income tax provision (benefit)	(3,617)	(2,659)	10,952	(4,666)
Net income (loss)	(10,495)	(7,341)	(42,250)	(12,960)
Oaxaca, Mexico
Income statement information
Exploration expense	767	1,540	1,850	3,974
Michigan, USA
Income statement information
Exploration expense	202	420	549	1,265
Operating Segments | Oaxaca, Mexico
Balance sheet information
Total current assets	20,419		20,419			25,155
Total non-current assets	41,400		41,400			62,368
Total assets	61,819		61,819			87,523
Total current liabilities	14,538		14,538			10,029
Total non-current liabilities	12,688		12,688			12,559
Total shareholders' equity	34,593		34,593			64,935
Total liabilities and shareholders' equity	61,819		61,819			87,523
Capital investments	7,500		7,500			11,000
Income statement information
Sales, net	13,272	20,552	52,756	76,587
Total mine cost of sales, including depreciation	21,907	24,359	67,081	77,395
Exploration expense	767	1,540	1,850	3,974
Total other costs and expenses, including G&A	1,294	166	2,909	869
Income tax provision (benefit)	(3,213)	(2,349)	10,970	(3,911)
Net income (loss)	(7,483)	(3,164)	(30,054)	(1,740)
Operating Segments | Michigan, USA
Balance sheet information
Total current assets	66		66			116
Total non-current assets	91,770		91,770			93,287
Total assets	91,836		91,836			93,403
Total current liabilities	51		51			59
Total non-current liabilities	69,148		69,148			62,792
Total shareholders' equity	22,637		22,637			30,552
Total liabilities and shareholders' equity	91,836		91,836			93,403
Capital investments	0		0			400
Income statement information
Total mine cost of sales, including depreciation	28	23	83	65
Exploration expense	202	420	549	1,265
Total other costs and expenses, including G&A	1,178	767	7,576	981
Income tax provision (benefit)	(369)	(42)	211	(479)
Net income (loss)	(1,039)	(1,168)	(8,419)	(1,832)
Corporate and Other
Balance sheet information
Total current assets	1,487		1,487			1,224
Total non-current assets	304		304			1,736
Total assets	1,791		1,791			2,960
Total current liabilities	1,290		1,290			1,237
Total non-current liabilities	422		422			517
Total shareholders' equity	79		79			1,206
Total liabilities and shareholders' equity	1,791		1,791			2,960
Capital investments	0		0			$ 0
Income statement information
Total mine cost of sales, including depreciation	7	581	23	1,778
Total other costs and expenses, including G&A	2,001	2,696	3,983	7,886
Income tax provision (benefit)	(35)	(268)	(229)	(276)
Net income (loss)	$ (1,973)	$ (3,009)	$ (3,777)	$ (9,388)