Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (3,178)	$ (3,336)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	155	279
Accretion of asset retirement obligation	66	59
Decrease (increase) in derivative at fair value, net		215
Gain on trading securities	(52)
Asset write off	54
Gain on sale of assets	(17)
Stock compensation	429	52
Changes in operating assets and liabilities from continuing operations:
Decrease in lease receivable	72	138
(Increase) decrease in prepaid expenses and other assets	(478)	43
(Increase) decrease in inventories	(1,500)	53
Decrease in other long-term assets	352	96
Decrease in reclamation liability	(87)	(1)
Increase (decrease) in accounts payable and accrued liabilities	669	(568)
Decrease in other current liabilities	(124)	(675)
Decrease in deferred revenue	(140)	(118)
Decrease in other long-term liabilities	(135)	(56)
Net cash used in operating activities	$ (3,914)	$ (3,819)

The increase (decrease) during the reporting period in the aggregate value of plant lease receivables.

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