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Formula: Nb
Element, transition metal
Specific gravity: 8.57
Hardness: 6
Colour: Silvery white
Solubility: Insoluble in nitric and hydrochloric acids
Melting point: 2,477oC
Boiling point: 4744oC
Abundance:
17 parts per million by mass, 3.7 parts per million by moles in the Earth's crust
4 parts per billion by mass, 50 part per trillion by moles in the Solar System
(ChC).
Niobium is not recognised as a valid mineral species by the IMA, although it has been reported in the native
state from a handful of terrestrial localities, and from the moon.
Niobium-bearing minerals include:
Oxides - the oxide anion is O2-
aeschynite
belyankinite
bismutocolumbite
calciosamarskite
cesiokenopyrochlore
clinofergusonite-(Nd)
columbite-(Fe)
columbite-(Mg)
columbite-(Mn)
dmitryvarlamovite
euxenite-(Y)
fergusonite
fluornatropyrochlore
gerasimovskite
hydrokenopyrochlore
hydropyrochlore
hydroxyplumbopyrochlore
isolueshite
lueshite
manganbelyankinite
microlite
natroniobite
nioboheftetjernite
pauloabibite
rossovskyite
stibiocolumbite
ternovite
vigezzite
Hydroxides
franconite
Arsenites - the arsenite anion is (As3+O3)3-
zimbabweite
Sorosilicates - (Si4+2O7)6- groups
belkovite
bornemanite
fersmanite
låvenite
nacareniobsite-(Y)
vuonnemite
Cyclosilicates - (Si4+nO3n)2n-
baotite
organovaite
organovaite-(Mn)
organovaite-(Zn)
vuoriyarvite-K
Inosilicates - single chain - (Si4+nO3n)2n-
niobophyllite
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