Crystal Selenite

Category

Sulfate mineral

Formula
(repeating unit)

CaSO₄·2H₂O

Crystal system

Monoclinic (2/m) Space Group: A2/a

Identification

Formula mass

172.17

Color

Brown green, Brownish yellow, Greenish, Gray green, Gray white

Crystal habit

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Cleavage

[010] Perfect, [100] Distinct, [011] Distinct

Fracture

Fibrous - Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos).

Mohs scalehardness

2

Luster

Pearly

Streak

white

Specific gravity

2.9

Optical properties

Biaxial (-) 2V=58

Refractive index

nα=1.519-1.521, nβ=1.522-1.523, nγ=1.529-1.53

Birefringence

δ =0.0090-0.0100

Other characteristics

non-radioactive, non-magnetic, Fluorescent.

References

^[1]