What is it made of? Yellow earth, or yellow ocher, is found in natural earth deposits which contain iron oxide minerals that are yellow in color.
Where does it come from? The mineral was mined in many places around the Mediterranean, but Vitruvius asserts that the best quality was found in Attica, the region around Athens.
How is it made? Yellow ocher was prepared by selecting certain pigmented areas from a mineral deposit and grinding and separating the mineral into a fine, even powder.
Fun fact! Yellow ocher can turn red when exposed to extreme heat. Many of the wall paintings at Pompeii that today appear red were in fact originally yellow, until the ocher in the paint was exposed to hot ash during the eruption of Mount Vesuvius in 79 CE.
What is it made of? Orpiment is a naturally occurring yellow sulphide of arsenic mineral. Its Latin name, auripigmentum, means “gold pigment.”
Where does it come from? Orpiment was mined in Hungary, Macedonia, along on the Black Sea coast of Turkey, and in Syria. It is often found with realgar (see Red).
How is it made? To make the pigment, the sulphide mineral is ground and separated into a fine, even powder.
Fun fact! Orpiment and realgar are closely related minerals, and particles of one are often to be found with those of the other when viewed under a microscope. The yellow-orange rock sample on display contains both orpiment and realgar.