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PLANT AND EQUIPMENT AND MINERAL PROPERTIES - Schedule of Summary of Mineral Properties (Details) - USD ($) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016
Property, Plant and Equipment [Line Items] |  |  |  |  |
Impairment of mineral properties held for sale | $ 200,000 | $ 0 | $ 3,799,000 | $ 0 |
Mineral properties | 83,539,000 |  | 83,539,000 |  | $ 92,625,000
Abandonment of mineral properties | 0 | $ 1,005,000 | 287,000 | $ 1,036,000 |
Uranerz ISR properties |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Mineral properties | 25,974,000 |  | 25,974,000 |  | 35,060,000
In-situ recovery total |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Mineral properties | 25,974,000 |  | 25,974,000 |  | 35,060,000
Sheep Mountain |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Mineral properties | 34,183,000 |  | 34,183,000 |  | 34,183,000
Roca Honda |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Mineral properties | 22,095,000 |  | 22,095,000 |  | 22,095,000
Other |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Mineral properties | 1,287,000 |  | 1,287,000 |  | 1,287,000
Conventional total |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Mineral properties | $ 57,565,000 |  | $ 57,565,000 |  | $ 57,565,000

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- Definition The adjustment to expense previously capitalized costs of drilling exploratory wells when proved reserves are not found or when the entity obtains information that raises substantial doubt about the economic or operational viability of the project. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 40 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6475089&loc=d3e66625-109467 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 35 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=66906256&loc=d3e66150-109466 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 40 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6475089&loc=d3e66584-109467 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6475089&loc=d3e66610-109467 + Details
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