Pargasite

(n.)
A dark green aluminous variety of amphibole, or hornblende.
  

General Information:
 Chemical Formula:
NaCa2(Mg,Fe++)4Al(Si6Al2)O22(OH)2
 Composition:
(Molecular Weight = 867.37 gm)
Sodium 2.65 % Na
Calcium 9.24 % Ca
Magnesium 8.41 % Mg
Aluminum 9.33 % Al
Iron 6.44 % Fe
Silicon 19.43 % Si
Hydrogen 0.23 % H 
Oxygen 44.27 % O 
 Empirical Formula:
NaCa2Mg3Fe2+Si6Al3O22(OH)2
 IMA Status:
Approved IMA 1978
 Locality:
Pargas, Finland.
 Name Origin:
Named after its locality.
Physical Properties:
 Cleavage:
[110] Perfect, [010] Perfect
 Color:
bluish green, brown, grayish black, light brown, or dark green.
 Density:
3.069 - 3.181, Average = 3.12
 Diaphaniety:
Transparent to translucent
 Habits:
Tabular - Form dimensions are thin in one direction., ,
 Hardness:
6 - Orthoclase
 Luster:
Vitreous (Glassy)
 Streak:
white
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