Ore Enrichment and Smelting of Copper

Copper rivals gold as one of the oldest metals employed by man. Its first use about 10,000 years ago was stimulated by the natural occurrence of the metal in lumps or leaves in exposed rock formations, so called “native copper”. These exposures enabled the fashioning of simple tools directly by hammering and heat working of these fragments, and in so doing signalled the end of the Stone Age [1]. The natural occurrence of elemental copper is a feature of its relatively low standard reduction potential of +0.158 volts, significantly below hydrogen in the electromotive series and hence relatively easily accumulated in elemental form as a consequence of normal geologic processes. This contrasts with the much more easily oxidized aluminum, which lies above hydrogen in the electromotive series with a reduction potential of - 1.71 volts, and hence is never found in elemental form in nature.