Ferrohornblende

General Information:
 Chemical Formula:
[ ]Ca2[Fe++4(Al,Fe+++)]Si7AlO22(OH)2
 Composition:
(Molecular Weight = 947.32 gm)
Calcium 8.46 % Ca
Aluminum 4.98 % Al
Iron 25.05 % Fe
Silicon 20.75 % Si
Hydrogen 0.21 % H 
Oxygen 40.53 % O 
 Empirical Formula:
Ca2Fe2+4Al0.75Fe3+0.25(Si7AlO22)(OH)2
 IMA Status:
Approved IMA 1978
Physical Properties:
 Cleavage:
[???] Perfect, [???] Distinct
 Color:
brown, green, greenish brown, or black.
 Density:
3 - 3.47, Average = 3.23
 Diaphaniety:
Translucent to opaque
 Habits:
Columnar - Forms columns, Massive - Fibrous - Distinctly fibrous fine-grained forms., Massive - Granular - Common texture observed in granite and other igneous rock.
 Hardness:
5-6 - Between Apatite and Orthoclase
 Luminescence:
Non-fluorescent.
 Luster:
Vitreous - Pearly
 Streak:
white
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