Quick Facts
Formation & Origin
Orpiment forms in the same geological environments as realgar: low-temperature hydrothermal veins, hot springs, and volcanic fumaroles. It's the arsenic trisulfide to realgar's arsenic tetrasulfide. Where you find one, you almost always find the other.
Orpiment's perfect basal cleavage produces thin, flexible sheets with a pearly luster on the cleavage surface. This property, combined with its brilliant golden-yellow color, made it historically important as a pigment. The name 'orpiment' comes from the Latin 'auripigmentum' (gold pigment). Ancient Roman and Egyptian artists used it despite its toxicity.
Alchermists called orpiment 'king's yellow' and valued it for its resemblance to gold. They believed the arsenic sulfides were close to gold in nature's hierarchy of matter, leading to extensive (and dangerous) experiments attempting to transform them into actual gold.
Identification Guide
Orpiment is identified by its vivid lemon to golden-yellow color, very low hardness (1.5), perfect cleavage producing flexible sheets, and pearly luster on cleavage surfaces. The combination of yellow color and extreme softness narrows identification significantly.
Distinguish from sulfur (lighter yellow, different crystal habit, melts easily), yellow calcite (much harder, effervesces in acid), and gold (metallic luster, much heavier, malleable). SAFETY: Contains arsenic. Handle carefully and wash hands after.
Spotting Fakes
Orpiment is not commonly faked. Like realgar, it can degrade with light exposure, though orpiment is somewhat more stable. Fresh specimens have vivid golden-yellow color. Oxidized or degraded material may appear pale or whitish. Specimens should be stored away from strong light. The association with realgar (red) on the same specimen is common and adds visual interest and collector value.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
Orpiment's connection to alchemy and its gold-like color give it associations with transformation, wealth, and personal power. Like realgar, it was used in Chinese traditional practices for protection and purification. IMPORTANT: Handle with care. Do not make gem elixirs. Contains arsenic. Display only, do not carry or sleep with this mineral.
Where It's Found
World-class crystal specimens alongside realgar
Excellent crystal groups
Historic source of pigment material
Volcanic sublimate specimens
Price Guide
Good to Know
Scratch test: At hardness 1.5, Orpiment can be scratched with a fingernail. This is a display specimen, not a wearable stone.
Sources: Found in 4 notable locations worldwide, from China to Russia.
Heft test: Orpiment has average mineral density (3.49). It feels about as heavy as you'd expect from a stone its size.
Related Minerals
Red arsenic sulfide partner, always found together
Fellow toxic sulfide with dramatic crystal habit
Similar yellow color, completely different chemistry