General Information:
Chemical Formula:SiO2·n(H2O)
Composition:(Molecular Weight = 87.11 gm)Silicon 32.24 %
SiHydrogen 3.47 %
H Oxygen 64.29 %
O Empirical Formula: SiO21.5(H2O)
Environment:Sedimentary and secondary from the alteration of high silica igneous extrusive rocks.
Locality:World wide occurrences.
Name Origin:From the Old Indian upala - "precious stone."
Physical Properties: Cleavage:None
Color:white, yellow, red, brown, or blue.
Density:1.9 - 2.3, Average = 2.09
Diaphaniety:Transparent to translucent to opaque
Habits:Amorphous - No crystalline form or imitative shape., Massive - Uniformly indistinguishable crystals forming large masses., Reniform - "Kidney like" in shape (e.g.. hematite).
Hardness:5.5-6 - Knife Blade-Orthoclase
Luminescence:Fluorescent, Short UV=greenish yellow, Long UV=white.
Luster:Vitreous - Dull
Streak:white
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