Shiny silvery metal, soft when pure. Resists corrosion due
to oxide film, attacked by hot, concentrated acids but resists fused
alkalis. Used in stainless steels and super-conductor alloys. The element niobium
was formerly known as "columbium".
Diagnostic tests:
An acid solution boiled with metallic tin gives a blue color which slowly
changes to brown on continued boiling and disappears on dilution. Most
flux reactions are not very good. Absorption Spectroscopy is used for
quantitative analysis and Energy Dispersive Analysis of X-rays (EDAX) is
used for qualitative analysis.
References
Emsley, J., 1991; THE ELEMENTS : Sec. Ed.,
Clarendon Press, Oxford, 251 p.
(* - Mineral Name Is Not IMA Approved)
(! - New Dana classification added or changed from Danas New Mineralogy)
(? - IMA Discredited Mineral Species Name)
There are 214 minerals with Nb in the Mineralogy Database.