General Information:
Chemical Formula:
(Na2,Ca)Al2Si4O12·6(H2O)
Composition:
(Molecular Weight = 552.45 gm)
Sodium 8.32 % Na
Calcium 7.25 % Ca
Aluminum 9.77 % Al
Silicon 20.34 % Si
Hydrogen 2.19 % H
Oxygen 52.13 % O
Empirical Formula:
Na2CaAl2Si4O12·6(H2O)
Environment:
Alteration product of basalts.
Locality:
Island of Cyprus.
Name Origin:
Named after the German mineralogist and chemist, Christian Gottlob Gmelin (1792-1860) of Turbingen, Germany.
Physical Properties:
Cleavage:
[1010] Good, [0001] Parting
Color:
white, reddish white, pink, greenish white, or flesh red.
Density:
2.03 - 2.17, Average = 2.09
Diaphaniety:
Transparent to translucent
Habits:
Crystalline - Coarse - Occurs as well-formed coarse sized crystals., Druse - Crystal growth in a cavity which results in numerous crystal tipped surfaces.,
Hardness:
4.5 - Between Fluorite and Apatite
Luminescence:
Piezoelectric.
Luster:
Vitreous - Dull
Streak:
white
More details...