Kyanite
VIII - Nesosilicates |
Name | Kyanite
(Disthene) |
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Chemistry | Al[6]Al[5][O|SiO4] = Al2SiO5 | |
Hardness | 4.5 (parallel to long axis), 6 - 7 (across the long axis) | |
Lustre | pearly - vitreous | |
Colour | blue, white, pink, colour often not constituent throughout the crystal | |
Streak | white | |
Density [g/cm3] | 3.6 | |
Crystal habit | triclinic, crystals flat, prismatic, often embedded in rocks | |
Cleavage, Fracture | [100] perfect, [010] distinct, fracture splintery | |
other characteristics and occurrences | polymorph (same chemistry,
different structure) with andalusite and sillimanite,
in Al-rich, metamorphic pegmatites (gneiss, schists) together with garnet, staurolite and mica |
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