Mineral - Columbite-(Fe)
Columbite-(Fe)
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
Fe²⁺Nb₂O₆
Unit Cell
a=14.27 b=5.73 c=5.05 Z=4
Physical Properties
Hardness
6
Streak
blackbrown
Density
Heavy (3,5-6)
Cleavage
Distinct after {100}, indistinct after {010}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
blackbrown
Birefringence
Luster
Vitreous
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pbcn (60)
Habit
prismatic, tabular
Formation
Magmatic, in HFSE pegmatites
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Columbite-(Fe), Columbite
Composition
Elements
Mass
Nb₂O₅
72.37
Ta₂O₅
5.26
SnO₂
0.67
FeO
15.04
MnO
5.97
CaO
0.58
Norway (Palache et al. 1952)
Groups and Members
Columbite-Supergroup
Columbite-Group