Compañia Minera Antamina S.A. is a Peruvian company which engages in the production of copper, zinc and molybdenum concentrates, and silver and lead by-products. In terms of volume of operations, the miner is one of the country's leading copper and zinc concentrate producers and operates one of the world's ten largest mines. Mining is done by conventional open-pit methods. Production and sales activities are carried out through the following operational units: a mine, a concentrator and auxiliary units, a tailings dam, a slurry pipeline and a port facility (Punta Lobitos). The company estimates a reserve base of around 550Mt. Minera Antamina is controlled by multinational resource group BHP Billiton Ltd. and Anglo-Swiss Glencore plc.