Orpiment should not be ingested. Orpiment is a deep orange-yellow colored arsenic sulfide mineral with formula As2S3. It is found in volcanic fumaroles, low temperature hydrothermal veins, and hot springs and is formed both by sublimation and as a byproduct of the decay of another arsenic mineral, realgar. It takes its name from the Latin auripigmentum (aurum ? gold pigmentum ? pigment) because of its deep-yellow color.