Arsenic trisulfide is the
inorganic compound with the formula
As2S3. It is a bright yellow solid that is insoluble in water. It also occurs as the mineral
orpiment (Latin: auripigment), which has been used as a pigment. It is produced in the analysis of arsenic compounds. It is a group V/VI, intrinsic p-type semiconductor and exhibits photo-induced phase-change properties. The other principal arsenic sulfide is As
4S
4, a red-orange solid known as the mineral
realgar.