Prepaids and Other, Net - Components of prepaids and other (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Prepaids
Insurance	$ 1,014	$ 1,847
Mining claims and permitting fees	891	417
License fees	186	259
Equipment mobilization	0	423
Other	56	252
Deposits	195	1,105
Total	2,342	4,303
Other assets
Equipment not in use	0	12,238
Royalty - advance payment	600	360
Prepaid supplies inventory	0	885
Total	$ 600	$ 13,483