Arsenic sesquisulfide occurs in nature as the mineral orpiment. It is used as a pigment; in the manufacture of infrared-transmitting glass; in semiconductors and photoconductors.
Arsenic trisulfide is the inorganic compound with the formula As2S3.It also occurs as the mineral orpiment, which has been used as a pigment called King's yellow. It is produced in the analysis of arsenic compounds.