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Finance costs and finance revenues (Tables) | 12 Months Ended
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Dec. 31, 2017
Disclosure of Finance costs and finance revenues [Abstract] |
Disclosure Of Detailed information about Finance cost and Finance revenues [Text Block] | These captions are made up as follows:
|  | 2017 |  | 2016 |  | 2015 |
|  | US$(000) |  | US$(000) |  | US$(000) |
Finance revenues: |  |  |  |  |  |  |  |  |  |
Interests on loans to associates, note 29(a) |  |  | 1,685 |  |  | 4,164 |  |  | 2,286 |
Interest on time deposits |  |  | 1,050 |  |  | 358 |  |  | 419 |
Interests on third parties loans |  |  | 813 |  |  | 489 |  |  | 492 |
Interests on tax claims |  |  | 153 |  |  | 487 |  |  | 1,297 |
Income from financial instruments |  |  | - |  |  | 743 |  |  | - |
Dividends income |  |  | - |  |  | 589 |  |  | 500 |
Other finance revenues |  |  | 43 |  |  | - |  |  | - |
|  |  | 3,744 |  |  | 6,830 |  |  | 4,994 |
Unrealized variation of the fair value related to contingent consideration liability (b) |  |  | 1,773 |  |  | - |  |  | 6,032 |
Total finance revenues |  |  | 5,517 |  |  | 6,830 |  |  | 11,026 |
Finance costs: |  |  |  |  |  |  |  |  |  |
Interest on borrowings |  |  | 27,052 |  |  | 18,668 |  |  | 17,875 |
Interest on loans |  |  | 1,056 |  |  | 4,643 |  |  | 5,565 |
Banking expenses |  |  | 552 |  |  | 319 |  |  | 366 |
Increase in debt issuance costs, note 16(g) |  |  | 480 |  |  | - |  |  | - |
Tax on financial transactions |  |  | 180 |  |  | 159 |  |  | 312 |
Interest on commercial obligations |  |  | 5 |  |  | 496 |  |  | 120 |
Other finance costs |  |  | 7 |  |  | 830 |  |  | 41 |
|  |  | 29,332 |  |  | 25,115 |  |  | 24,279 |
Accrual of debt issuance costs, note 16(g) |  |  | 909 |  |  | - |  |  | - |
Accrual of the present value for mine and exploration project closure, note 15(b) |  |  | 4,382 |  |  | 4,116 |  |  | 3,293 |
Unrealized variation of the fair value related to contingent consideration liability (b) |  |  | - |  |  | 2,349 |  |  | - |
Total finance costs |  |  | 34,623 |  |  | 31,580 |  |  | 27,572 |
Disclosure of contingent liabilities in business combination [text block] | A reconciliation of fair value measurement of the contingent consideration liability is provided below:
|  | 2017 |  | 2016 |  | 2015 |
|  | US$(000) |  | US$(000) |  | US$(000) |
Beginning balance |  |  | 19,343 |  |  | 16,994 |  |  | 23,026 |
Variation of the fair value in results |  |  | (1,773) |  |  | 2,349 |  |  | (6,032) |
Final balance |  |  | 17,570 |  |  | 19,343 |  |  | 16,994 |
Disclosure Of significant unobservable valuation inputs [Text Block] | Significant unobservable valuation inputs are provided below:
|  | 2017 |  | 2016 |
Annual average of future sales of mineral (US$000) |  |  | 193,588 |  |  | 233,278 |
Useful life of mining properties |  |  | 13 |  |  | 13 |
Discount rate (%) |  |  | 10 |  |  | 10 |

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