Cash flow information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net loss	$ (25,383)	$ (18,823)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, depletion and amortization	(4,480)	(3,128)
Gain on sale of assets, net	(719)	(689)
Accretion of asset retirement obligation	198	200
Asset write off	27	138
Write off of loss contingency, net	(1,969)	(1,645)
Decrease in warrant liability	(1,344)	(1,693)
Decrease in derivative liability	(553)
Amortization of deferred loan costs	54
Impairment of long lived assets	13,181
Foreign exchange gain on loss contingency	(106)	(281)
Stock compensation	453	926
Changes in operating assets and liabilities:
(Increase) decrease in trade accounts receivable	(546)	25
Decrease in prepaid expenses and other assets	384	287
Decrease (increase) in inventories	861	(764)
Increase in accrued interest payable net of amounts capitalized	81
Decrease in value added tax receivable (net)	916	449
(Decrease) increase in accounts payable and accrued liabilities	(402)	358
Increase in deferred revenue	500
(Decrease) increase in deferred leasehold payments	(11)	42
Decrease in reclamation liability	(37)	(117)
Net cash used in operating activities	$ (9,935)	$ (18,459)