Orpiment
Orpiment is a sulfide mineral recognized among collectors for its crystal form and distribution, with several world-class Chinese localities.
About Orpiment
Orpiment belongs to the sulfide class in the orpiment group and has the chemical formula As2S3. It crystallizes in the monoclinic system and is relatively soft, requiring careful handling. Its combination of structural character and global distribution make it a recognized species in both systematic and aesthetic collections.
Identification & care
Specimens usually show platy, foliated, columnar; massive, powdery, botryoidal; flexible cleavage plates. Its color is typically lemon-yellow to golden-yellow and orange-yellow. The luster is resinous, pearly (on cleavage surfaces), subadamantine, the streak is pale yellow, and specimens range from translucent to transparent. The cleavage is perfect on {010} — flexible but not elastic plates. The fracture is uneven, which aids identification.
Collector context
How it forms
The geological setting for Orpiment is typically low-temperature hydrothermal veins, hot spring sinters, fumarolic deposits; forms in reducing arsenic-rich environments. It is commonly found in association with realgar, stibnite, cinnabar, pyrite, calcite, native arsenic.
Classic Chinese localities
**Shimen deposit** is a benchmark source for orpiment.
Why collectors care
Orpiment is a frequently-sought species in serious collections because its habit is recognizable, its color often strong, and its best examples unmistakable even at a distance. Chinese material has driven much of the recent visual shift in the species — sharper crystals, deeper colors, cleaner matrix.
What affects value
Value in Orpiment is assessed, in typical order of weight, against: (1) locality provenance; (2) size relative to the species norm; (3) crystal form and termination sharpness; (4) color saturation and zoning; (5) transparency and internal clarity; (6) matrix quality and aesthetic balance; (7) condition (absence of damage, chips, or repair). Cleaning quality and verified locality documentation act as multipliers across the above.
Naming history
The name Orpiment has a specific etymological and historical context — see Mindat's reference entry for provenance details. We have retained naming data at the record level; published prose is paraphrased from factual fields rather than copied from source.