Gold, the only yellow metal, is rare, beautiful and doesn’t tarnish. The chemical symbol for gold is Au, derived from the Latin word for gold – aurum – meaning shining dawn. Its main uses are in jewellery, dentistry, to adorn buildings or for other artistic purposes but gold is also used in electronics.
In jewellery, gold is a satisfying metal to work for it casts well and can be shaped with simple tools that have hardly changed over many years. Gold’s softness and relatively low melting point make it easy to work into exquisite jewellery.
Of all the world’s countries, it may surprise to know that Italy and India produce the most gold jewellery each year.
Gold jewellery is measured in carats, the purest form of which is 24 carat, which means about 999 parts per thousand of the metal used is gold. Mostly this is made into ingots because pure gold is soft and needs to be alloyed with other metals to increase its strength.
Wedding rings generally use 22-carat gold (916 parts per thousand, the balance is made up of other metals) and other high quality jewellery uses 18-carat gold (750 parts per thousand). Less expensive jewellery is often made using 9-carat gold (375 parts per thousand).
Even when gold represents only about 50% of metal used in a piece of jewellery, it remains highly resistant to tarnish.
Only about 2,000 tonnes a year is mined from the earth but a little gold goes a long way. Gold is so malleable that one troy ounce (31.16 grams) can be hammered into gold leaf so thin it covers 134 square metres. It is also so ductile, that the same amount can be drawn into a fine wire 80 kilometres long.
Gold is also used in electronic and computer circuitry, radar equipment and satellites. When man first landed on the moon in the Apollo 14 lunar module, his vehicle had a film coating of gold because of its ability to reflect intense heat. The metal is used extensively in microchips because it is an excellent conductor of electricity.
Learn how KCGM produces this extraordinary metal in these pages.
For an educational mining presentation please click here.