Composition: Iron manganese magnesium niobium tantalum oxide
Nomenclature: Named after its major chemical constituents, columbium (now niobium) and tantalum.
Industrial Uses: Ore of niobium (columbium) and tantalum.
Additional Notes: Columbite forms a series with the mineral tantalite. Columbite is the end-member with more niobium (at one time niobium was called columbium, hence the name columbite); tantalite is the end-member with more tantalum. Since columbite and tantalite exhibit very similar properties and since a detailed chemical analysis is generally needed to distinguish the two minerals, specimens from the series are typically referred to as "columbite-tantalite."
Uganda : Scott 599 : 1 shilling : 18 Jan 1988
Columbite-tantalite