Hastingsite

General Information:
 Chemical Formula:
NaCa2(Fe++4Fe+++)Si6Al2O22(OH)2
 Composition:
(Molecular Weight = 990.86 gm)
Sodium 2.32 % Na
Calcium 8.09 % Ca
Aluminum 5.45 % Al
Iron 28.18 % Fe
Silicon 17.01 % Si
Hydrogen 0.20 % H 
Oxygen 38.75 % O 
 Empirical Formula:
NaCa2Fe2+4Fe3+(Si6Al2O22)(OH)2
 Environment:
Nepheline-syenite rocks.
 IMA Status:
Approved IMA 1978
 Locality:
Dungannon, Hastings Co., Ontario, Canada.
 Name Origin:
Named after its locality.
Physical Properties:
 Cleavage:
[110] Perfect, [110] Perfect
 Color:
dark green or black.
 Density:
3.17 - 3.59, Average = 3.38
 Diaphaniety:
Transparent to translucent
 Habits:
Tabular - Form dimensions are thin in one direction., ,
 Hardness:
6 - Orthoclase
 Luminescence:
Non-fluorescent.
 Luster:
Vitreous (Glassy)
 Streak:
greenish gray
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