Making Orpiment Yellow Pigment — Grinding the Golden Arsenic Mineral of the Ancient World

Orpiment (arsenic trisulfide, As₂S₃) is one of the most brilliant and beautiful yellow pigments ever used by painters — its name derives from the Latin 'auripigmentum' (gold pigment), because its warm, intense golden-yellow colour was the closest available imitation of gold before modern synthetic yellows existed. It occurs naturally as a bright yellow, often lustrous mineral in volcanic fumaroles, hot springs, and hydrothermal veins, and has been mined and used as a pigment since at least 3000 BC in ancient Egypt, Mesopotamia, and China.

Orpiment was the yellow of choice for ancient manuscript illumination, wall painting, and decorative art across the ancient and medieval world. Chinese and Persian painters used it extensively, and it appears in Egyptian tomb paintings, Roman wall decorations, and Byzantine manuscripts. Its colour is extraordinary: a pure, warm, brilliant yellow with excellent opacity and tinting strength.

SAFETY WARNING: Orpiment is an ARSENIC COMPOUND and is EXTREMELY TOXIC. Arsenic is a potent carcinogen and cumulative poison — even small repeated exposures through inhalation or skin contact can cause serious illness. The mineral MUST be ground WET (never dry) to prevent dust. Wear a P100 respirator with organic vapour cartridges, chemical splash goggles, and chemical-resistant gloves at ALL times when handling. Work outdoors or under a fume hood. Wash all equipment and surfaces with wet cloths — never sweep. Dispose of ALL waste water and materials as hazardous waste. This pigment is incompatible with lead-based and copper-based pigments — it reacts to form dark-coloured arsenic compounds, blackening the painting.