Tantalite: The mineral columbite-tantalite information and pictures

About

Tantalite forms a solid solution series with Columbite known as the Columbite-Tantalite series. Tantalite is the tantalum-rich member, and Columbite is the niobium-rich member. Tantalite is named after its tantalum content, and, together with Columbite, are the most important minerals containing the rare element tantalum.

The name Tantalite has been discredited by the IMA, with the more specific designations of Tantalite-(Fe) (also known as Ferrotantalite), and Tantalite-(Mn) (also known as Manganotantalite) being used for this mineral's IMA-accepted nomenclature. Ferrotantalite is always dark and opaque; Manganotantalite is usually reddish-brown and may exhibit transparency. An even rarer member of this series is Tantalite-(Mg) (Magnesiotantalite), a magnesium-rich member. In general, despite being discredited, the name Tantalite 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 and tabular crystals, often with a somewhat flattened or blocky appearance. 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.

Striking Features

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

Environment

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

Varieties

✓ generally accepted · ✗ less commonly used

Manganotantalite— Manganese-rich member of the Tantalite sub-series in the Columbite-Tantalite solid solution series. Known by the IMA as Tantalite-(Mn).

Polymorphs

Tapiolite

Uses

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

Noteworthy Localities

Localities for Tantalite are pretty much the same as Columbite, and it often is not identified individually but more generally as Columbite-Tantalite. Specific localities that have produced exceptional Tantalite include the São Pedro Mine, Malacacheta, Minas Gerais, Brazil, where it was found in blocky crystals; the Shigar Valley, Skardu, Gilgit-Baltistan, Pakistan, as pseudomorphs of Microlite; and Ankole, Mbarara District, Uganda; where the manganese-rich end member has been found in dark red, translucent crystals.

Common Mineral Associations

Albite, Orthoclase, Quartz, Microcline, Muscovite, Samarskite

Distinguishing Similar Minerals

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