monoclinic Sulfides
Orpiment
Formula As2S3
Crystal Structure
#! Species: Orpiment
#! System: Monoclinic (2/m)
#! Habit: Tabular to prismatic, micaceous cleavage
monoclinic[2/m]:{010}@1.0 + {100}@0.5 + {001}@0.7 + {110}@0.4
monoclinic
2/m
{010} {100} {001} {110}
Quick Facts
Hardness
1.5
Specific Gravity
3.46
Refractive Index
2.4
Optical Character
Biaxial -
Physical Properties
- Crystal System
- monoclinic
- Hardness (Mohs)
- 1.5
- Specific Gravity
- 3.46
- Cleavage
- Perfect {010} (produces thin flexible sheets)
- Fracture
- Sectile (can be cut with knife)
- Lustre
- Resinous to pearly (on cleavage)
Optical Properties
- Refractive Index
- 2.4
- Birefringence
- 0.62
- Optical Character
- Biaxial -
- Pleochroism
- Strong dichroic (yellow to greenish-yellow)
Characteristics
Colours
Lemon yellowGolden yellowOrange-yellow
Localities
China (Hunan)PeruRussia (Kamchatka)TurkeyRomaniaNevada (USA)
Crystal Forms
pinacoidprismfoliated masses
Notes
CAUTION - contains arsenic; extremely high birefringence; handle with care; wash hands after handling
Related Minerals
Other minerals in the monoclinic system
