Orpiment

Orpiment is a mineral. Its chemical formula is As₂S₃. It is an orange to yellow mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity of 3.46. It melts at 300°C and oxidizes to arsenic trioxide at higher temperatures. It is toxic because it gets a layer of arsenic trioxide on it by oxidation in the air.

Orpiment was used as a pigment because it was one of the only yellow pigments that they could find. It is used to remove hair from hides.

Orpiment Media

Streak color of Orpiment
Orpiment and Realgar on the same rock
Raphael (1483–1520), Sistine Madonna (1513-14)
Anonymous, The Wilton Diptych (c 1395-9), The National Gallery, London.
Jacopo Tintoretto (c 1518-1594), Portrait of Vincenzo Morosini, The National Gallery (Presented by the Art Fund), London.
Giovanni Bellini (c 1430–1516) and Titian (–1576), The Feast of the Gods (1514-1529), National Gallery of Art, Washington, DC. Wikimedia Commons.
Orpiment's unit cell
Orpiment's crystal structure consists of sheets
The sheets are stacked into layers
Orpiment from Racha, northern Georgia region