General Information:
Chemical Formula:
Ca2Al(AlSi)O7
Composition:
(Molecular Weight = 274.20 gm)
Calcium 29.23 % Ca
Aluminum 19.68 % Al
Silicon 10.24 % Si
Oxygen 40.84 % O
Empirical Formula:
Ca2Al2SiO7
Environment:
Trentino, Italy.
Locality:
Contact metamorphic mineral in limestone.
Name Origin:
Named after the German chemist, A. F. Gehlen (1775-1815).
Physical Properties:
Cleavage:
[001] Good
Color:
brown, colorless, greenish, gray, or yellow.
Density:
2.9 - 3.07, Average = 2.98
Diaphaniety:
Transparent to translucent
Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Tabular - Form dimensions are thin in one direction., Massive - Granular - Common texture observed in granite and o ther igneous rock.
Hardness:
5-6 - Between Apatite and Orthoclase
Luster:
Vitreous - Greasy
Streak:
white
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