INDIALITE
Class : Silicates
Subclass : Cyclosilicates
Crystal system : Hexagonal
Chemistry : Mg2Al4Si5O18
Rarity : Very rare
Indialite is a dimorphic silicate of cordierite. Much rarer than the latter, indialite is formed in sedimentary rocks melted by the spontaneous combustion of coal seams. It is also known in cordierite veins in a highly metamorphic andalusite and sillimanite rock (Unazuki, Japan). Its name comes from its country of discovery : India. It forms small hexagonal grains and small spiral aggregates that are colorless to pale purplish pink.
Main photo : Indialite from Caspar quarry, Bellerberg, Germany © Volker Betz
Indialite in the World
Twinning
No twins known for this mineral species.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 7 to 7.5
Density : 2.51
Fracture : Undeterminated
Streak : White
TP : Transparent
RI : 1.534 to 1.539
Birefringence : 0.005
Optical character : Uniaxial -
Pleochroism : None
Fluorescence : None
Solubility : -
Magnetism : NoneRadioactivity : None