Mineral - Boracite
Boracite
Chemical Properties
Mineral Class
Borates
Toxicity
none
Formula
Mg₃[Cl|BO₃|B₆O₁₀]
Unit Cell
a=8.58 b=8.55 c=12.09 Z=4
Physical Properties
Hardness
7 - 7.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
graygreencolorless
Birefringence
0.010
Luster
Vitreous,
Adamantine
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-pyramidal - mm2
Space Group
Pca2 1 (29)
Habit
dodecahedron, fibrous, Octahedron, Tetrahedron, Cube
Formation
Evaporitic
Paragenesis
Twinning
Penetration twins after {111}
Rarity
Rarely
Synonyms
Boracite
Composition
Elements
Mass
B₂O₃
59.68
FeO
1.09
MgO
26.38
MgCl₂
12.17
Germany (Palache et al. 1952)
Groups and Members
Boracite-Group