CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Cash and cash equivalents	$ 131,987	$ 141,984
Materials and supplies inventories, net – Note 3	2,746	2,808
Prepaids and deposits – Note 4	2,048	2,840
Income tax receivable	1,530	1,530
Interest receivable	512	459
Accounts receivable	0	2,771
Current assets	138,823	152,392
Property, plant and equipment, net – Note 5	54,381	54,832
Restricted cash – Note 6	34,308	33,982
Assets held for sale – Note 7	7,148	7,148
Prepaids – Note 4	600	600
Total assets	235,260	248,954
Liabilities:
Accounts payable and accrued expenses	4,562	5,644
Debt, net – Note 8	2,328	2,328
Contract liabilities - Note 7	1,050	1,050
Other liabilities – Note 9	1,254	3,011
Current liabilities	9,194	12,033
Debt, net – Notes 8 and 18	135,072	132,690
Deferred gain on sale of royalty	29,837	29,837
Asset retirement obligation – Note 10	10,488	10,302
Warrant liabilities – Notes 11 and 12	133	786
Total liabilities	184,724	185,648
Commitments and contingencies – Note 20
Stockholders’ equity:
Common stock, $0.0001 par value; 1,400,000,000 shares authorized; 200,270,659 issued and outstanding at March 31, 2023, and 200,270,659 issued and outstanding at December 31, 2022 – Note 12	20	20
Additional paid-in capital – Note 12	734,576	733,437
Accumulated deficit	(684,060)	(670,151)
Total stockholders’ equity	50,536	63,306
Total liabilities and stockholders’ equity	$ 235,260	$ 248,954