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Amounts Receivable (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Receivables [Line Items] |  |
Other receivables | $ 4.0 | $ 3.7
Trade and other current receivables | 34.5 | 44.9
Canada |  |
Receivables [Line Items] |  |
Sales tax receivables | 6.4 | 2.3
Mexico |  |
Receivables [Line Items] |  |
Sales tax receivables | 20.0 | 36.2
Other |  |
Receivables [Line Items] |  |
Sales tax receivables | 0.9 | 0.5
Concentrate receivable | $ 3.2 | $ 2.2

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