General Information:
Chemical Formula:
(Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6
Environment:
Basic igneous and metamorphic rocks.
IMA Status:
Approved IMA 1980
Locality:
Common world wide.
Name Origin:
From the Greek auge - "luster."
Physical Properties:
Cleavage:
[110] Perfect, [010] Indistinct
Color:
brown green, green, light brown, dark brown, or black.
Density:
3.2 - 3.6, Average = 3.4
Diaphaniety:
Translucent to opaque
Habits:
Massive - Fibrous - Distinctly fibrous fine-grained forms., Columnar - Forms columns, Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Hardness:
5-6.5
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Resinous
Streak:
greenish gray
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