Pre-payment facility	12 Months Ended
Dec. 31, 2017
Disclosure of Pre-payment facility [abstract]
Pre-payment facility	10. Pre-payment facility On January 29, 2017, the Company entered into a pre-payment facility for $15.0 million with Metagri S.A. de C.V., a subsidiary of Glencore PLC (“Glencore”), to fund a portion of the development costs for the San Rafael project within the Cosalá district of Sinaloa, Mexico (the “Pre-Payment Facility”). The Pre-Payment Facility was drawn in full on March 30, 2017, has a term of four years at an interest of U.S. LIBOR rate plus 5% per annum, and is secured by a promissory note in the amount of up to $15.0 million issued by the Company, a corporate guarantee in favour of Glencore, and limited asset level security on the San Rafael project. The Company has also entered into four-year offtake agreements with Glencore for the zinc and lead concentrates produced from the San Rafael project where Glencore will pay for the concentrates at the prevailing market prices for silver, zinc and lead, less customary treatment, refining and penalty charges. Principal on the Pre-Payment Facility will be repaid beginning in January 2018 as an additional tonnage charge on shipments of concentrate with minimum annual principal repayments of $4.0 million during 2018, $5.5 million during 2019, and $5.5 million during 2020.

10. Pre-payment facility

On January 29, 2017, the Company entered into a pre-payment facility for $15.0 million with Metagri S.A. de C.V., a subsidiary of Glencore PLC (“Glencore”), to fund a portion of the development costs for the San Rafael project within the Cosalá district of Sinaloa, Mexico (the “Pre-Payment Facility”). The Pre-Payment Facility was drawn in full on March 30, 2017, has a term of four years at an interest of U.S. LIBOR rate plus 5% per annum, and is secured by a promissory note in the amount of up to $15.0 million issued by the Company, a corporate guarantee in favour of Glencore, and limited asset level security on the San Rafael project. The Company has also entered into four-year offtake agreements with Glencore for the zinc and lead concentrates produced from the San Rafael project where Glencore will pay for the concentrates at the prevailing market prices for silver, zinc and lead, less customary treatment, refining and penalty charges. Principal on the Pre-Payment Facility will be repaid beginning in January 2018 as an additional tonnage charge on shipments of concentrate with minimum annual principal repayments of $4.0 million during 2018, $5.5 million during 2019, and $5.5 million during 2020.