Mineral - Gaudefroyite
Gaudefroyite
Chemical Properties
Mineral Class
Borates
Toxicity
none
Formula
Ca₄Mn³⁺₃[O₃|CO₃|(BO₃)₃]
Unit Cell
a=10.59 c=5.89 Z=2
Physical Properties
Hardness
6
Streak
brown
Density
Normal (2-3,5)
Cleavage
Distinct after {11 2 0}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
blackbrown
Birefringence
0.210
Luster
Vitreous
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
hexagonal
Point Group
hexagonal-pyramidal - 6
Space Group
P6 3 (173)
Habit
blocky, acicular, prismatic, barrel-shaped
Formation
hydrothermal
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Gaudefroyite
Composition
Elements
Mass
B₂O₃
16.93
CO₂
6.57
Mn₂O₃
40.73
CaO
35.06
H₂O
0.63
Morocco (Jouravsky & Permingeat 1964)