<P> The ISO 4217 currency code of gold is XAU . Many holders of gold store it in form of bullion coins or bars as a hedge against inflation or other economic disruptions . Modern bullion coins for investment or collector purposes do not require good mechanical wear properties; they are typically fine gold at 24k, although the American Gold Eagle and the British gold sovereign continue to be minted in 22k (0.92) metal in historical tradition, and the South African Krugerrand, first released in 1967, is also 22k (0.92). </P> <P> The special issue Canadian Gold Maple Leaf coin contains the highest purity gold of any bullion coin, at 99.999% or 0.99999, while the popular issue Canadian Gold Maple Leaf coin has a purity of 99.99% . In 2006, the United States Mint began producing the American Buffalo gold bullion coin with a purity of 99.99% . The Australian Gold Kangaroos were first coined in 1986 as the Australian Gold Nugget but changed the reverse design in 1989 . Other modern coins include the Austrian Vienna Philharmonic bullion coin and the Chinese Gold Panda . </P> <P> As of September 2017, gold is valued at around $42 per gram ($1,300 per troy ounce). </P> <P> Like other precious metals, gold is measured by troy weight and by grams . The proportion of gold in the alloy is measured by karat (k), with 24 karat (24k) being pure gold, and lower karat numbers proportionally less . The purity of a gold bar or coin can also be expressed as a decimal figure ranging from 0 to 1, known as the millesimal fineness, such as 0.995 being nearly pure . </P>

Who discovered the element gold and in what year