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MINERAL PROPERTY INTERESTS - Mineral Property Interests (Details) - USD ($) $ in Thousands |  |  | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2018 | Apr. 19, 2016 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Aug. 25, 2017
Mineral Property Interests |  |  |  |  |  |
Payments to aquire mineral propety interests |  |  | $ 18,983 | $ 3,492 | $ 5,985 |
Additional to mineral properties |  |  | 19,400 | 3,300 |  |
Impairment charges |  |  |  | 711 |  |
Mineral property interests |  |  | 309,145 | 293,437 |  |
Amortization of mineral property interests and asset retirement obligations |  |  | 7,256 | 3,198 | 2,413 |
Black Fox |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 16,365 | 11,364 |  |
Black Fox | Production costs applicable to sales |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Amortization of mineral property interests and asset retirement obligations |  |  | 5,100 |  | 0 |
Lexam VG Gold |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 41,595 | 41,595 |  |
Los Azules Copper Project |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 191,490 | 191,490 |  |
Tonkin Properties |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 4,833 | 4,833 |  |
El Gallo 1 mine | Production costs applicable to sales |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Amortization of mineral property interests and asset retirement obligations |  |  | 2,100 | 2,300 | $ 2,400 |
El Gallo Project |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 4,139 | 6,246 |  |
Fenix Project Properties |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 5,807 | 5,807 |  |
El Gallo 2 project |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Impairment charges |  |  |  | 700 |  |
Battle Mountain Complex Located In Nevada United States |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | 785 | 785 |  |
Gold Bar project |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  | $ 44,131 | 31,317 |  |
Royalty |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Total purchase price at closing |  | $ 6,300 |  |  |  |
Payments to aquire mineral propety interests | $ 1,000 | 5,300 |  |  |  |
Royalty | El Gallo 1 mine |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Additional to mineral properties |  | 5,100 |  |  |  |
Royalty | El Gallo 2 project |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Additional to mineral properties |  | $ 1,200 |  |  |  |
Black Fox |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Mineral property interests |  |  |  |  |  | $ 8,954
Black Fox | Production costs applicable to sales |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Amortization of mineral property interests and asset retirement obligations |  |  |  | 900 |  |
Mexico |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |
Impairment charges |  |  |  | $ 711 |  |

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- Definition Represents the amount of amortization expense related to the mineral property interests and capitalized asset retirement costs. + References No definition available. + Details
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