Mineral - Columbite-(Mn)
Columbite-(Mn)
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
Mn²⁺Nb₂O₆
Unit Cell
a=14,43 b=5,76 c=5,08 Z=4
Physical Properties
Hardness
6
Streak
blackred
Density
Very Heavy (>6)
Cleavage
Deutlich auf (100), weniger deutlich auf (010)
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
blackbrown
Birefringence
Luster
Vitreous,
Metallic
Transparency
translucent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
Space Group
Habit
prismatic, tabular
Formation
In granitischen Pegmatiten
Paragenesis
Twinning
Kontaktzwillinge auf (021) und (023), pseudohexagonale Rotationszwillinge
Rarity
Rather rare
Synonyms
Columbite-(Mn), Columbite
Composition
Elements
Mass
Nb₂O₅
68,10
Ta₂O₅
9,87
TiO₂
0,54
SnO₂
0,89
FeO
5,46
MnO
14,80
Na₂O
0,02
South Dakota (Palache et al. 1952)
Groups and Members
Columbit-Supergruppe
Columbit-Gruppe