General Information:
Chemical Formula:
(Na,Ca)2Nb2O6(OH,F)
Composition:
(Molecular Weight = 353.84 gm)
Sodium 9.75 % Na
Calcium 5.66 % Ca
Niobium 52.51 % Nb
Hydrogen 0.21 % H
Oxygen 30.52 % O
Fluorine 1.34 % F
Empirical Formula:
Na1.5Ca0.5Nb2O6(OH)0.75F0.25
Environment:
Nepheline-syenite rocks.
IMA Status:
Approved IMA 1977
Locality:
Fredriksvarn and Larvik, Norway.
Name Origin:
From the Greek pyr - "fire" and chloros - "green."
Physical Properties:
Cleavage:
[111] Indistinct, [111] Indistinct, [111] Indistinct
Color:
brown, yellowish brown, yellow, greenish brown, or reddish brown.
Density:
4.2 - 6.4, Average = 5.3
Diaphaniety:
Subtranslucent to opaque
Habits:
Granular - Generally occurs as anhedral to subhedral crystals in matrix., Disseminated - Occurs in small, distinct particles dispersed in matrix.,
Hardness:
5-5.5 - Apatite-Knife Blade
Luminescence:
None.
Luster:
Resinous - Greasy
Streak:
yellowish brown
More details...