Indialite

Formula:  Mg₂Al₄Si₅O18

Origin of name:  Locality; India

Crystal system:  Hexagonal

Crystal class:  6/m 2/m 2/m

Twinning: 

Unit cell: a = 9.812, c = 9.351

Colour:  Colourless to pale mauve in thin section

Diaphaneity:  Transparent

Luster:  Vitreous

Habit:  Crystals hexagonal prisms, minute; grains, small and irregular

Hardness:  7 to 7.5

Specific gravity:  2.51

Cleavage:  None

Tenacity: 

Streak: White

Synonyms/varieties:

Comments:  Dimorphous with cordierite