Author name: Charles R. M. Butt

Gold is an element, a metal and a mineral. In nature, gold most commonly occurs as an alloy with silver and, more rarely, with palladium, mercury and copper, and ranges in size from nanoparticles to nuggets weighing 70 kg. Crystallography, metallography and composition control the colour of the alloy, how it will deform, how it will behave at high temperature and how it reacts. These properties offer insights into how gold deposits have formed and been altered, whether under hydrothermal or Earth-surface conditions.

Gold has fascinated people of most cultures since earliest times because of its colour, seeming immutability and ease of fabrication into exquisite objects. Due to gold’s rarity, its principal functions have been as currency and a store of wealth. Most of the gold ever mined has been hoarded, and rich discoveries over the past 160 years have increased the notional global amount per capita two to five fold. This rate of inflation is minor in comparison to that of currency, so gold still performs its historical financial role. Research is directed at discovering new deposits to support this role, and at finding practical applications commensurate with its monetary cost.