Color

Colorless

Crystal system

Trigonal - Hexagonal
Scalenohedral H-M Symbol32/m
Space Group: R3c

Lattice constant

a_rh   = 5.85 Å     a` = 103 20`
a_hex = 4.59 Å
c_hex = 14.87 Å

Cleavage

[1011] perfect

Mohs scale hardness

3.5 - 4.5

Diaphaneity

Transparent to translucent

Specific gravity

3.0 - 3.2

Optical properties

Unixial (-)

Refractive index

n_ಎ= 1.508 - 1.510
n_ԑ= 1.700