(the colours of cooper)

Turquoise is a characteristically blue-to-green gem. It is a hydrated copper aluminium phosphate mineral. Copper is at the source of its bright blue colour, but it may also be modified through chemical reactions with other substances, or even by heat or light. When any of these unfortunate things happen, it is said that the turquoise "dies". Therefore, it should be handled carefully and the use of cosmetics or detergents should be avoided.

Malachite (copper carbonate) is a semi-precious stone of a very bright and intense green colour where clear and dark shades alternate in parallel bands or concentric rings. Its colour is also due to copper. It is very heavy (almost four times as heavy as water) and not too hard. All this allows it to be beautifully polished which, together with its colour, makes it a very chatoyant material. This stone should also be kept away from acid materials and sources of heat.

The word turquoise is thought to have arisen from the fact that the ancient trade route along which turquoise was brought to Persia (Iran) went through Turkey. It is also found in the Sinai, Australia, Tibet, and Arizona. It is often faked by dyeing or "reconstructing" other stones. As far as malachite is concerned, it was mainly found in the Urals, from where it was extracted to decorate the palaces of the Russian Tsars. Big amounts of malachite were later found in places such Africa, the most important being Katanga (Congo). Other places include Australia, Chile, Zimbabwe, South Africa, and Arizona.

Both malachite and turquoise were very much prized in Antiquity. The Egyptians, the Greek, and the Romans used them as ornate stones, amulets, or even as eye make-up powder. These civilizations believed malachite and turquoise had magical and protective powers.

Other bright-coloured stones which are linked to copper are Chrysocolla (also known as Peruvian turquoise) and Eliat Stone (Israel), a variegated mixture of chrysocolla, turquoise, and malachite.