Ochre
A natural earth pigment coloured by iron oxide, ranging from yellow through orange to red.
Also: yellow ochre, red ochre, geru
Ochre is clay tinted by iron oxide. With water bound into the mineral it is yellow; heat drives the water off and turns it red, which is how red ochre can be made from yellow. People have used it for at least a hundred thousand years, in burials, body paint and rock art across Africa, Australia, Europe and the Americas. Aboriginal Australians still mine and trade it for ceremony. In India a red ochre called geru colours floors, walls and the robes of some ascetics. It is cheap, permanent and safe to handle.