Mineral - Andradite
Andradite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Ca₃Fe³⁺₂[SiO₄]₃
Unit Cell
a=12.10 Z=8
Physical Properties
Hardness
6.5 - 7
Streak
white
Density
Normal (2-3,5)
Cleavage
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
blackbrownredgreen
Birefringence
Luster
Adamantine,
Resinous
Transparency
translucent,
transparent,
opaque
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
In skarns, through contact metamorphism (metasomatism), in green schists and serpentinites, in magmatic alkali plutonites
Paragenesis
Twinning
Rarity
Common
Synonyms
Andradite
Composition
Elements
Mass
SiO₂
34.91
TiO₂
0.01
Al₂O₃
0.69
Fe₂O₃
30.40
MgO
0.58
CaO
33.20
H₂O
0.19
Serbia (Dana 1892)
Groups and Members
Garnet-Supergroup
Garnet-Group
Name and first discovery : Named after the Brazilian mineralogist José Bonifácio de Andrada e Silva (1763-1838). First described in its current form in 1868.
Chemistry :
Synonyms : Allochroite, Jelleite, Jellesite, Lime Iron Clay Garnet
Varieties : Bredbergite, Colophonite, Demantoid, Hydroandradite, Melanite, Polyadelpite, Topazolite, Titano-Andradite
Abbreviation : Adr
literature
Dana, J. D., & Dana, E. S. (1892). The system of mineralogy of James Dwight Dana, 1837-1868: descriptive mineralogy . J. Wiley & sons.