General Information:
Chemical Formula:
Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4
Composition:
(Molecular Weight = 1,422.09 gm)
Calcium 28.18 % Ca
Magnesium 3.42 % Mg
Aluminum 7.59 % Al
Silicon 17.77 % Si
Hydrogen 0.28 % H
Oxygen 42.75 % O
Empirical Formula:
Ca10Mg2Al4(Si2O7)2(SiO4)5(OH)4
Environment:
Contact metamorphic rocks and alpine veins.
IMA Status:
Approved IMA 1960
Locality:
Mte. Somma, Vesuvius, Italy.
Name Origin:
Named after its locality.
Physical Properties:
Cleavage:
[110] Indistinct, [100] Indistinct, [001] Indistinct
Color:
blue, brown, green, yellow, or white.
Density:
3.35 - 3.45, Average = 3.4
Diaphaniety:
Subtransparent to subtranslucent
Habits:
Massive - Uniformly indistinguishable crystals forming large masses., Columnar - Forms columns, Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Hardness:
6.5 - Pyrite
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Resinous
Streak:
white
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