Macaulayite is a red, earthy, monoclinic mineral, with the chemical formula (Fe3+, Al)24Si4O43(OH)2. It was discovered in the 1970s by Jeff Wilson and named after the Macaulay Institute in Aberdeen, Scotland. The only known source of macaulayite in the world is a quarry at the foot of Bennachie, Aberdeenshire, and it is formed by granite which has been weathered by tropical climates from before the last ice age. The substance is currently being studied by NASA, as it is speculated that this is the substance which gives the planet Mars its colour and it could prove that life on Mars can be sustained.