Annual report pursuant to Section 13 and 15(d)

Mineral Properties - rollforward (Details)

v3.10.0.1
Mineral Properties - rollforward (Details) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Balance at beginning of period $ 44,677,000 $ 47,029,000
Acquisition costs 31,000 18,000
Increase in reclamation costs 2,840,000 448,000
Change in estimated reclamation costs (Note 13) 2,840,000 448,000
Amortization (1,743,000) (2,818,000)
Balance at end of period 45,805,000 44,677,000
Lost Creek Project    
Balance at beginning of period 11,810,000 14,015,000
Increase in reclamation costs 2,577,000  
Change in estimated reclamation costs (Note 13) 2,500,000 613,000
Amortization (1,743,000) (2,818,000)
Balance at end of period 12,644,000 11,810,000
Pathfinder properties    
Balance at beginning of period 19,701,000 19,866,000
Increase in reclamation costs 263,000 (165,000)
Balance at end of period 19,964,000 19,701,000
Other U.S. Properties [Member]    
Balance at beginning of period 13,166,000 13,148,000
Acquisition costs 31,000 18,000
Balance at end of period $ 13,197,000 $ 13,166,000