Arsen Sulfide
As2S3
Chemical name
Arsen Sulfide
Mineral name
Orpiment
Chemical formula
As2S3
Melting point [°C]
300 - 325
Crystal system
monoclinic
Crystal Class
monoclinic-prismatic (2/m)
Space Group
P2_1/n
Unit cell
a [Å]:11.48
b [Å]:9.58
c [Å]:4.26
Molecular weight [g/mol]
246,06
Formula units
Z=4
Frequent crystal surfaces
{100}, {010}, {301}, {110}, {011}, {210}
Mohs hardness
1.5 - 2
Density [g/cm3]
3.49
Cleavage
perfect on {010}, imperfect on {100}
Fracture / Tenacity
sectile
Color
yellow to golden or brownish-yellow
Streak
pale lemon-yellow
Transparency
transparent
Optical character
biaxial (-)
Refractive Index
nα=2.400; nβ=2.810; nΥ=3.020
Birefringence δ
0.620
Pleochroism δ
strong
Piezoelectric crystals
 
T(c) [°C]
nω = 1.564–1.595,