Where do metals come from?

Most pure metals, like aluminium, silver and copper, come from the Earth’s crust. They are found in ores – solid materials called minerals, usually occurring in rock, from which the pure metal has to be extracted. The properties of pure metals can be improved by mixing them with other metals to make alloys.

Metals are often divided into:

• ferrous metals, which have iron in them (for example mild steel, carbon steel and cast iron)

• non-ferrous metals, which don’t have iron in them (for example copper, aluminium, tin and lead).  

People first began making things from metal over 6000 years ago, when they discovered how to get copper from its ore. They then learned how to make a harder alloy, bronze, by adding tin to the copper. About 3000 years ago, they discovered iron. By adding small amounts of carbon to iron, they found that they could make a particularly useful alloy – steel.

Thus technologists and designers have known about, and used, pure metals and alloys for many millennia. However, they have only understood metals’ atomic structure quite recently. These days we know about some 100 pure metals and a large number of alloys, all of which have a wide range of properties. The metals you’re mostly likely to use in school are:

• aluminium alloy

• copper

• brass

• silver

• mild steel

• carbon steel

The first stage in making metals is to mine the ore-bearing rock. Sometimes huge amounts of ore are needed to make a small amount of metal – most copper, for example, exists in sulphide ores that contain as little as 0.25% copper. The metal then has to be extracted from the rock using furnaces and electrolytic processes. Finally, before the metal can be used, it often has to undergo further processing. For example, 98% pure ‘blister copper’, created by smelting and reduction, then has to be ‘electrorefined’ to produce copper of 99.99% purity.