Columbite

Radioactive

Yttrocolumbite

Ferrocolumbite-pb50a

Face-centered orthorhombic

Columbite, also known as niobite, niobite-tantalite and columbate (Fe, Mn)Nb2O6, is a black mineral group that is an ore of niobium. It has a submetallic luster and a high density and is a niobate of iron and manganese. This mineral group was first found in Haddam, Connecticut, in the United States. It forms a series with the tantalum-dominant analogue ferrotantalite and one with the manganese-dominant analogue manganotantalite.

Properties

Columbite has an orthorhombic crystal system, which is a type of crystal system where the crystal axes are of unequal lengths but are at right angles to each other. The hardness of columbite on the Mohs scale of mineral hardness is 6 to 6.5, which indicates that it is somewhat resistant to scratching. The specific gravity of columbite ranges from 5.2 to 6.3, making it a heavy mineral.

Occurrence

Columbite is found in granite pegmatites and alkaline granites. These are igneous rocks that are rich in rare elements like niobium and tantalum. The mineral is usually associated with other rare minerals like lithium, cesium, and beryllium. The largest columbite deposits are found in Africa, particularly in Nigeria, Congo (Kinshasa), and Rwanda. Other significant deposits are located in Brazil, Canada, and Australia.

Uses

Columbite is primarily used as a source of niobium. Niobium is used to produce high-grade structural steel and superalloys, which are materials that can withstand high temperatures and are resistant to corrosion and oxidation. These superalloys are used in jet engines, rocket subassemblies, and heat-resisting and combustion equipment. Niobium is also used in the production of superconductors and in the electronics industry.

Environmental and Health Concerns

The mining of columbite affects the environment through deforestation, soil erosion, and contamination of water sources. The process of extracting niobium and other metals from columbite can also release toxic substances into the environment. Workers in columbite mines may be exposed to harmful dust, which can lead to respiratory problems.

See Also

• Tantalite
• Niobium
• Mining in Africa
• Pegmatite

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