Gehlenite

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
More details...

B: (Kimia) gehlenit
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