Copper

Currently, the most common source of copper ore is the mineral chalcopyrite (CuFeS2), which accounts for about 50％ of copper production. To a large extent, copper oxide and sulfides are naturally separated in nature. As such, once mined the processing of the ore generally does not need to separate the oxides and sulfides. Copper ore bodies are formed when hydrothermal solutions bring copper dissolved from deep underground to cool near surface environments where the copper and associated metals precipitate as minerals in veins and disseminations within the rock. Copper is usually deposited as copper sulfide minerals or in some environments as native copper metal. In prehistory, copper could be found as native copper on the surface of the ground. Prospecting for copper in this environment was relatively simple. Over time, increased demand has meant that mining has turned to more marginal forms of copper to continue supply. These marginal copper sources are also much more difficult to locate. When a copper body is discovered, drilling is undertaken to determine the size and proportion of copper in the ore body zones (i.e. the grade). If the copper ore deposit is typical, it will be described in terms of the number of tonnes (and the grade) of ore in each of the oxide, secondary and primary zones. The tonnes and grade can be multiplied together to determine the amount of copper in the deposit, and the processing costs for each zone can be used to determine mine profitability.