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DERIVATIVE INSTRUMENTS (Details 2) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
GAIN (loss) on the provisional pricing of concentrate sales |  |
Realized | $ (8.9) | $ 11.9
Unrealized | (1.6) | 4.2
Total gain (loss) | (10.5) | 16.1
Gold [Member] |  |
GAIN (loss) on the provisional pricing of concentrate sales |  |
Realized | (1.2) | 1.9
Unrealized | 1.1 | 0.1
Total gain (loss) | (0.1) | 2.0
Copper [Member] |  |
GAIN (loss) on the provisional pricing of concentrate sales |  |
Realized | (7.7) | 10.0
Unrealized | (2.7) | 4.1
Total gain (loss) | $ (10.4) | $ 14.1

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- Definition The gains (losses) on the provisionally pricing of concentrate sales which realised during the reporting period. + References No definition available. + Details
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- Definition Totals gains (losses) on the provisionally pricing of concentrate sales which recognised during the reporting period. + References No definition available. + Details
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