Iolite
Also called cordierite, dichroite and water sapphire
Iolite is named after it's violet color. The other names come form the French mineralogist,
Cordier; and from it's similarity to sapphire. Greasy, virtreous luster care must be taken
when cutting because of the strong pleochroism. Stones must not be too thick. Main
deposits ate in Burma, Brazil, Sir Lanka, India, and Malagasy Republic.
- Color : Blue in various hues
- Color or streak : White
- Mohs' hardness : 7-7 1/2
- Specific gravity : 2.58-2.66
- Cleavage : Imperfect
- Fracture : Conchoidal, uneven, brittle
- Crystal system : Orthorhombic; short prisms
- Chem. Comp. : Mg2Al3(AlSi5O18) magnesium aluminum silicate
- Transparency : Transparent, translucent
- Refractive index : 1.559-1.631
- Double refraction : +0.072
- Dispersion : 0.015
- Pleochroism : None
- Absorption spectrum : Not useable
- Flourescence : None