Ferroholmquistite

General Information:
 Chemical Formula:
[ ](Li2Fe++3Al2)Si8O22(OH)2
 Composition:
(Molecular Weight = 846.07 gm)
Lithium 1.64 % Li
Aluminum 6.38 % Al
Iron 19.80 % Fe
Silicon 26.56 % Si
Hydrogen 0.24 % H 
Oxygen 45.38 % O 
 Empirical Formula:
Li2Fe2+3Al2(Si8O22)(OH)2
 IMA Status:
Approved IMA 1978
 Name Origin:
The name reflects its composition and relationship to holmquistite..
Physical Properties:
 Color:
black.
 Hardness:
5-6 - Between Apatite and Orthoclase
More details...