Mineral - Colemanite
Colemanite
Chemical Properties
Mineral Class
Borates
Toxicity
none
Formula
Ca[B₃O₄(OH)₃]·H₂O
Unit Cell
a=8.71 b=11.25 c=6.09 β=110° Z=2
Physical Properties
Hardness
4.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {010}, distinct after {001}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
brownyellowcolorless
Birefringence
0.028
Luster
Vitreous,
Adamantine
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
blocky, crusty, prismatic, Rhombohedron, Rhombohedral, tabular
Formation
Sedimentary (in Borax-Lakes)
Paragenesis
Twinning
Rarity
Common
Synonyms
Colemanite
Composition
Elements
Mass
B₂O₃
50.70
MgO
0.10
CaO
27.31
H₂O
21.87
California (Palache et al. 1951)