Indialite - Encyclopedia

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 by Nickenicher Weinberg, Eifel, Germany © Volker Betz

Indialite of Vesuvius, Naples, Italy © Christophe Boutry

Indialite in the World

Occurrences of indialite are very rare. In addition to that of Unazuki (Japan), it is known in a "molten" rock with enstatite, magnetite and corundum in contact with a consumed coal mine in Bokaro (India). Rare other localities are also reported, notably in Germany (Bellerberg volcano) and in the United States (Pyramid Lake, Nevada).

Indialite in France

Indialite is not present in the French underground.

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