Denisovite

General Information:
 Chemical Formula:
(K,Na)Ca2Si3O8(F,OH)
 Composition:
(Molecular Weight = 345.98 gm)
Potassium 8.48 % K 
Sodium 1.66 % Na
Calcium 23.17 % Ca
Silicon 24.35 % Si
Hydrogen 0.07 % H 
Oxygen 38.15 % O 
Fluorine 4.12 % F 
 Empirical Formula:
K0.75Na0.25Ca2Si3O8F0.75(OH)0.25
 IMA Status:
Approved IMA 1982
Physical Properties:
 Cleavage:
[???] Indistinct
 Color:
greenish gray or gray.
 Density:
2.76
 Hardness:
4-5 - Fluorite-Apatite
 Luster:
Pearly
 Streak:
gray white
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