General Information:
Chemical Formula:
Al2SiO5 = Al[6]Al[4]OSiO4
Composition:
(Molecular Weight = 162.05 gm)
Aluminum 33.30 % Al
Silicon 17.33 % Si
Oxygen 49.37 % O
Empirical Formula:
(Al2O3)(SiO2)
Environment:
Metamorphosed peri-aluminous sedimentary rocks.
Locality:
Wide spread world wide occurrences.
Name Origin:
Named after the American chemist and mineralogist, B. Silliman (1779-1824).
Physical Properties:
Cleavage:
[010] Perfect
Color:
bluish, brownish greenish, colorless, gray, or gray green.
Density:
3.24
Diaphaniety:
Transparent to translucent
Habits:
Fibrous - Crystals made up of fibers., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Acicular - Occurs as needle-like crystals.
Hardness:
7 - Quartz
Luminescence:
None.
Luster:
Vitreous (Glassy)
Streak:
white
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