Mineral - Grossular
Grossular
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Ca₃Al₂[SiO₄]₃
Unit Cell
a=11.85 Z=8
Physical Properties
Hardness
6.5 - 7
Streak
white
Density
Normal (2-3,5)
Cleavage
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
blackbrownredyellowgreencolorless
Birefringence
Luster
Vitreous,
Resinous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
isometric
Point Group
hexoctahedral - 4/m 3 2/m
Space Group
Ia 3 d (230)
Habit
Deltoidal icositetrahedron, dodecahedron
Formation
Through contact metamorphism or regional metamorphism of silica-rich limestones
Paragenesis
Twinning
Rarity
Common
Synonyms
Grossular, Hessonite, Hydrogrossular, Tsavorite
Composition
Elements
Mass
SiO₂
39.30
Al₂O₃
21.93
Fe₂O₃
0.80
Cr₂O₃
0.13
FeO
0.28
MgO
0.01
CaO
37.10
H₂O
0.30
California (Dana 1895)
Groups and Members
Garnet-Supergroup
Garnet-Group