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Embedded Derivatives (Details) | 6 Months Ended
--- | ---
Jun. 30, 2018 oz t $ / oz $ / t
Gold |
Embedded Derivative [Line Items] |
Under contract | oz | 8,928
Average forward price | $ / oz | 1,318
Silver |
Embedded Derivative [Line Items] |
Under contract | oz | 891,195
Average forward price | $ / oz | 16.61
Copper |
Embedded Derivative [Line Items] |
Under contract | t | 740
Average forward price | $ / t | 6,934
Lead |
Embedded Derivative [Line Items] |
Under contract | t | 2,941
Average forward price | $ / t | 2,440
Zinc |
Embedded Derivative [Line Items] |
Under contract | t | 7,959
Average forward price | $ / t | 3,263

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