Material extracted from the Company’s mine is classified as either process material or waste. Process material represents mineralized material that, at the time of extraction, the Company expects to process into a saleable form and sell at a profit, while waste is considered uneconomic to process and its extraction cost is included in direct mining costs. Raw materials are comprised of process material stockpiles. Process material is accumulated in stockpiles that are subsequently processed into bulk copper, silver, and gold concentrate in a saleable form. The Company has bulk copper, silver, and gold concentrate inventory in saleable form that has not yet been sold. Mine operating supplies represent commodity consumables and other raw materials used in the production process, as well as spare parts and other maintenance supplies that are not classified as capital items.
Inventories are valued at the lower of cost and net realizable value. Cost is determined on a weighted average basis and includes all costs incurred, based on normal production capacity, in bringing each product to its present location and condition. Cost of inventories comprises direct labor, materials and contractor expenses, depletion and depreciation on mining properties, plant and equipment, and an allocation of mine site costs. As mineralized material is removed for processing, costs are removed based on the average cost per tonne in the stockpile. Stockpiled process material tonnages are verified by periodic surveys.
Net realizable value (“NRV”) of mineralized material is determined with reference to relevant market prices less applicable variable selling expenses and costs to bring the inventory into its saleable form. NRV of materials and supplies is generally calculated by reference to salvage or scrap values when it is determined that the supplies are obsolete. NRV provisions are recorded within cost of sales in the consolidated statement of operations, and are reversed to reflect subsequent recoveries where the inventory is still on hand.