Orpiment is a bright yellow to orange-yellow arsenic sulfide mineral with the chemical formula As2S3. It’s known for its historical use as a pigment, often called “king’s yellow,” but its toxicity due to arsenic content limits its use today.
Historically, orpiment was a significant yellow pigment in art, but its use has declined due to its toxicity. Its use in art is documented in various ancient civilizations, including Egypt, Persia, and China. It was used as a paint pigment up through the 18th and 19th century.
Key Characteristics:
Composition: It’s a sulfide of arsenic, meaning it contains arsenic and sulfur.
Color: Orpiment’s color ranges from a lemon yellow to a deep orange-yellow, sometimes described as golden. The name “orpiment” is derived from the Latin “auripigmentum,” meaning “golden paint,” reflecting its color.
Occurrence: It’s found in volcanic fumaroles, low-temperature hydrothermal veins, and hot springs. Orpiment is often found in association with another arsenic sulfide mineral called realgar.
Toxicity: Orpiment is toxic due to its arsenic content.
Instability: It is unstable and can decompose when exposed to light and air.
