Orpiment (lat. auripigmentum, gold pigment), mineral, is found in small, rhombic crystals, mostly coarse, scattered, in lodes, bulbous, clustered, kidney-shaped, is not very translucent, lemon or bitter orange yellow, with a faint oily sheen, hardness 1.5 to 2, specific weight 3.4 to 3.5, consists of arsenic sulfide As2S3 and is found in Hungary and Transylvania, with realgar, quartz and calcite in marls and clayey sandstones, with galena, pyrites etc. on ore veins, also on veins in clay slate, at Andreasberg, in Wallachia, China, Mexico, in crater fissures on Etna and Vesuvius. About artificial auripigment see Arsenic sulphides.

Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909