Columbite: The mineral columbite-tantalite information and pictures

About

Columbite forms a solid solution series with Tantalite known as the Columbite-Tantalite series. Columbite is the niobium-rich member, and Tantalite is the tantalum-rich member. Columbite is named after its niobium content, which was previous known as columbium prior to its renaming. Columbite is the most important mineral containing the rare element niobium and is its main ore.
The name Columbite has been discredited by the IMA, with the more specific designations of Columbite-(Fe) (also known as Ferrocolumbite), and Columbite-(Mn) (also known as Manganocolumbite) being used for this mineral's IMA-accepted nomenclature. Most Columbite specimens are of the Ferrocolumbite; Manganocolumbite is far less common. An even rarer member of this series is (Columbite-(Mg) (Magnesiocolumbite), a magnesium-rich member. In general, despite being discredited, the name Columbite is still used without further designation, and often it is simply labelled as Columbite-Tantalite, since the exact species can be difficult to determine.

Crystal Forms & Aggregates

In prismatic crystals, often with a somewhat flattened appearance. Tabular or equant habits are less common. Crystals may be striated or have growth patterns, and sometimes have complex terminations including uneven tapering habits and pyramidal. Crystals are often crudely formed and may have undefined faces. Also bladed, grainy, and massive.

Other ID Marks

May exhibit weak attraction to magnetic fields.

Striking Features

Crystal habit, mode of occurrence, and high specific gravity.

Environment

In granite pegmatites, as well as alluvial deposits containing weathered pegmatite fragments.

Uses

Columbite is as an ore of the rare elements niobium and tantalum.

Noteworthy Localities

Columbite occurs in many of the important pegmatite districts worldwide. It has been found in many locations in Minas Gerais, Brazil, especially at Araçuaí; Governador Valadares; and São José da Safira. Other important worldwide locations include the Tsaramanga pegmatite, Betafo District, Antananarivo Province, Madagascar; and Iveland, Aust-Agder, Norway.
In the U.S., many of the old pegmatite quarries have produced some of the best forms of this mineral. Specific localities include Bethel, Fairfield Co.; Haddam and Portland, Middlesex Co.; South Glastonbury, Hartford Co.; and Woodbury, Litchfield Co. Other U.S. localities include the Ham and Weeks Mine, Wakefield, Carroll Co., New Hampshire; Bedford, Westchester Co., New York; the Rutherford Mine, Amelia, Amelia Co., Virginia; and Spruce Pine, Mitchell Co., North Carolina.

Common Mineral Associations

Albite, Orthoclase, Quartz, Microcline, Muscovite, Samarskite

Distinguishing Similar Minerals

Tantalite - Greater specific gravity.Uraninite - Is radioactive, forms in different crystal habits.Schorl - Lower specific gravity, greater hardness.Wolframite - Lacks perfect cleavage.