Arsenic trisulfide with a brilliant yellow color and pearly luster. Was historically used as a pigment kings yellow . Color: Golden yellow to lemon yellow. Luster: Resinous to pearly. Streak: Pale yellow. Cleavage: Perfect in one direction. Hardness: 1.5-2. Transparency: Transparent to translucent. Crystal system: Monoclinic. Chemical formula: As₂S₃. Specific gravity: 3.49. Formation: Forms in low-temperature hydrothermal veins and hot spring deposits, often with realgar. Common geological settings: China, Peru, Turkey, Russia; found in volcanic fumaroles and hot springs. Common look-alikes and related entries: Sulfur, Realgar, Autunite. Specimen safety: Keep this arsenic-bearing specimen intact. Do not cut, grind, polish, streak, lick, heat, or use acid on it. Avoid creating or breathing dust or fumes, wash your hands with soap and water after handling, and keep it away from food, children, and pets.
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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GeoMiner
Last updated
2026-03-30T14:36:59.982588+00:00
Review status
Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Arsenic (inorganic compounds, as As) — CDC/NIOSH. Official occupational-hazard, exposure-route, symptom, and protective-equipment information for inorganic arsenic compounds.
Arsenic trisulfide with a brilliant yellow color and pearly luster. Was historically used as a pigment kings yellow .
How can you identify Orpiment?
Compare several properties rather than relying on colour alone. This entry records colour: Golden yellow to lemon yellow; lustre: Resinous to pearly; streak: Pale yellow; Mohs hardness: 1.5-2; cleavage: Perfect in one direction; crystal system: Monoclinic; transparency: Transparent to translucent. Confirm an important identification with additional field tests or qualified laboratory work.
How does Orpiment form?
Forms in low-temperature hydrothermal veins and hot spring deposits, often with realgar.
Where is Orpiment commonly found?
China, Peru, Turkey, Russia; found in volcanic fumaroles and hot springs.
Is Orpiment safe to handle?
Keep this arsenic-bearing specimen intact. Do not cut, grind, polish, streak, lick, heat, or use acid on it. Avoid creating or breathing dust or fumes, wash your hands with soap and water after handling, and keep it away from food, children, and pets. Avoid creating dust or using destructive tests on an unknown specimen, and follow site-specific safety procedures.
What is Orpiment commonly confused with?
Orpiment may be confused with Sulfur, Realgar, Autunite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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