Pigment Names
Mineral Names:	Chinese: ci huang or shi huang (pinyin), tz'u huang or shih huang English: orpiment French: orpiment German: Rauschgelb, Operment Italian: orpimento Japanese: shiō, kiō, sekiō Russian: аурипигмент Spanish: oropimente
Artificial Pigment Names:	English: king's yellow French: juane royal, orpin artificiel German: Königsgelb Russian: желтый мышьяк
Synonyms:	English: arrhenicum, arsenic trisulfide, arsenikon, auripigment, auripigmento, auripigmentum, jalde, operment, oropiment, yellow arsenic French: arsenic jaune, arsenic sulfuré jaune German: Arsenblende, Arsenikon, Auripigment, Gelbe Arsenblende Greek: studied the mechanisms of deterioration in orpiment. Several medieval painting guides do not recommend mixing orpiment with lead white, red lead or verdigris. However, it must also be noted that it has been identified in paintings mixed with indigo, red iron oxide, azurite, Prussian blue, green bice (artificial malachite), and bice (smalt). It cannot be applied to wet plaster, and hence is not recommended in wet fresco painting techniques. Oil Absorption and Grinding No data has been published on the oil absorption properties of orpiment. It is difficult to grind because of its micaceous structure. For this reason, it is often quite coarse. It has been suggested to add ground glass to the pigment to facilitate grinding and dispersion in linseed oil. Toxicity The toxicity of arsenic sulfide pigments has been known for years. Extreme caution must be used when handling the dry orpiment pigment, as well as in any soluble form, to avoid inhaling the dust or ingesting it. Pigment: Orpiment Pigment Information Color: Yellow Colour Index: Pigment Yellow 39 (77085, 77086) Chemical Name: Arsenic Sulfide Chemical Formula: As2S3 ASTM Lightfastness Rating Acrylic: Not Rated Oil: Not Rated Watercolor: Not Rated Properties Density: 3.49 g/cm3 Hardness (Mohs): 1.5–2.0 Refractive Index: nα = 2.400 nβ = 2.810 nγ = 3.020