Occurrence of Metals

In general, pure metals are shiny and malleable, but most metals are found in nature as compounds rather than free elements, and how reactive a metal is decides which form it occurs in. Metals with the least chemical reactivity -- copper, silver, gold and platinum -- occur in nature in significant amounts as native elements, essentially unreacted with their surroundings. Reactive metals, such as the alkali metals, occur only in a combined state (as oxides, sulphides, chlorides, silicates and similar compounds) and must be extracted using a suitable metallurgical process.

Extracting a metal of interest from its ore consists of the following broad steps:

1. Concentration of the ore -- removing the unwanted rocky/earthy material (gangue) to enrich the ore in the metal-bearing mineral. …