Malachite

This green rock is the naturally occurring source of all copper. Unlike gold, which can be found in the ground in its elemental state, copper needs to be extracted from its ore – malachite. Extraction is done by a process of smelting where malachite is heated with carbon to extract the oxygen from the copper oxide that is found within the rock. This leaves behind nuggets of metallic copper, which can be melted down and purified to produce copper that is ready for use in applications like electrical wiring. The surface of copper easily oxides, as it re-bonds with the oxygen in our atmosphere, and as a result tarnishes and will eventually turn green again – in effect, returning to a state of malachite.