Gold
60000 usd/kgGold is revered for its properties: a combination of colour, corrosion resistance, weight and malleability. While it is biocompatible and suitable for implanting in the body (such as to repair or cap teeth as a dental alloy), and its superior conductivity is used in precision electronics applications, the majority ends up in jewellery and tableware.
Its resistance to corrosion and tarnishing sets it apart from other conductive and malleable metals, like copper and silver. Its high resistance to corrosion means that it maintains it performance over time, giving consistent and reliable results.
The purity of gold is measured in carats (ct or c), also karats (kt or k), and is defined by the % weight of gold in the metal: 24 ct pure gold, 23 ct is 95.8% gold, 22 ct is 91.7% gold, 21k is 87.5% gold, 20 ct is 83.3% gold, 19 ct is 79.2% gold, 18 ct is 75% gold,14 ct is 58.3% gold and 10 ct is 41.1% gold.
For parts that are not required to be solid gold, it can be plated onto the surface of another metal. For example, in applications where it is not practical to use gold, such as for weight or strength reasons, or if it would be too expensive or unnecessary.
The carbon footprint and embodied energy (resource use) are eye-watering – much higher than other engineering materials. They are surpassed only by rhodium (Rh) and platinum (Pt). Much of this is the result of the mining practices and energy consumed during refinement and production. Gold is difficult to extract from its ore.