Realgar is an ancient pigment used in ancient Egypt and Mesopotamia. It was the only pure orange pigment until modern chrome orange.

A red-orange natural pigment closely related to yellow orpiment and the two minerals are found in the same deposits. Realgar was once widely used as a pigment because of its bright rich color.

It is extremely toxic arsenic disul de, which limited its range of application and availability.

Alongside orpiment, it was a signi cant item of trade in the ancient Roman Empire. Early occurrences of realgar as a red painting pigment are known for works of art from China, India, Central Asia, and Egypt. It was used in European painting during the Renaissance, but its use died out by the 19th century.

It was used as a rat poison in medieval Europe and in China was frequently sprinkled around houses to repel snakes and insects.

The Chinese name for realgar is ‘masculine yellow’, as opposed to the ‘feminine yellow’ of orpiment.

Realgar is not particularly stable and can also deteriorate badly in oil paint lms, resulting in rupturing, cracking and chalking.