Mineral - Spessartine
Spessartine
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Mn₃Al₂[SiO₄]₃
Unit Cell
a=11.62 Z=8
Physical Properties
Hardness
7 - 7.5
Streak
white
Density
Heavy (3,5-6)
Cleavage
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
blackredorangeyellow
Birefringence
Luster
Vitreous,
Greasy
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, Octahedron, Cube
Formation
(1) Magmatic, formed by fractional crystallization in manganese-rich, peralkaline, or peraluminous granites and their associated pegmatites.
(2) Metamorphic, formed under low- to medium-pressure and temperature conditions (green schist to amphibolite facies) through the alteration of manganese-bearing sediments or in contact metasomatic skarns.
Paragenesis
Twinning
Rarity
Common
Synonyms
Spessartine
Composition
Elements
Mass
SiO₂
35.33
TiO₂
0.01
Al₂O₃
21.50
FeO
0.01
MnO
41.06
MgO
0.01
CaO
1.02
H₂O
0.86
Japan (Dana 1895)
Groups and Members
Garnet-Supergroup
Garnet-Group