General Information:
Chemical Formula:
(Ca,Na)4(Ti,Nb)2Si2O11(F,OH)2
Composition:
(Molecular Weight = 543.48 gm)
Sodium 1.06 % Na
Calcium 27.65 % Ca
Titanium 13.21 % Ti
Niobium 8.55 % Nb
Silicon 10.34 % Si
Hydrogen 0.09 % H
Oxygen 33.85 % O
Fluorine 5.24 % F
Empirical Formula:
Ca3.75Na0.25Ti1.5Nb0.5Si2O11F1.5(OH)0.5
Environment:
Associated with feldspar and aegirite in veins in nepheline-syenite.
Locality:
Chibines Mountains, Kola peninsula, Russia.
Name Origin:
Named for Alexander Yevgenievich Fersman (1883-1945), Russian mineralogist and geochemist.
Physical Properties:
Cleavage:
None
Color:
golden yellow, resin brown, light brown, or dark brown.
Density:
3.44
Diaphaniety:
Transparent to translucent
Habits:
Pseudo Tetragonal - Crystals show a tetragonal shape., ,
Hardness:
5.5 - Knife Blade
Luster:
Vitreous (Glassy)
Streak:
brownish white
More details...