General Information:
Chemical Formula:
(K,Na)3(Mn,Fe++)7(Ti,Nb)2Si8O24(O,OH)7
Composition:
(Molecular Weight = 1,333.33 gm)
Potassium 6.60 % K
Sodium 1.29 % Na
Titanium 5.39 % Ti
Manganese 21.63 % Mn
Niobium 3.48 % Nb
Iron 7.33 % Fe
Silicon 16.85 % Si
Hydrogen 0.23 % H
Oxygen 37.20 % O
Empirical Formula:
K2.25Na0.75Mn2+5.25Fe2+1.75Ti1.5Nb0.5Si8O28(OH)3
Locality:
Lovozero massif, Kola Peninsula, Russia.
Name Origin:
Named for Boris Mikhailovich Kupletski (1984-1964) and Elsa Maximilianove Bohnshtedt Kupletskaya (1897-1974), Russian geologists.
Physical Properties:
Cleavage:
[001] Perfect
Color:
yellow brown, black, or black brown.
Density:
3.2 - 3.23, Average = 3.21
Diaphaniety:
Translucent to Opaque
Habits:
Tabular - Form dimensions are thin in one direction., Acicular - Occurs as needle-like crystals.,
Hardness:
4 - Fluorite
Luster:
Vitreous - Adamantine
Streak:
brown
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