Mineral - Danburite
Danburite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Ca[B₂Si₂O₈]
Unit Cell
a=8.04 b=8.75 c=7.73 Z=4
Physical Properties
Hardness
7 - 7.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Indistinct after {001}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
whiteredyellow
Birefringence
0.006
Luster
Vitreous,
Greasy
Transparency
transparent
Pleochroism
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pnma (62)
Habit
blocky, massive, prismatic, tabular
Formation
hydrothermal, Metamorphism
Paragenesis
Twinning
Rarity
Common
Synonyms
Danburite, Bementite
Composition
Elements
Mass
SiO₂
49.18
B₂O₃
27.65
Al₂O₃
0.42
FeO
0.26
MnO
0.02
MgO
0.11
CaO
22.10
SrO
0.03
Na₂O
0.07
H₂O
0.24
Slovakia (Dana 1892)