Columbite, also called niobite, niobite-tantalite and columbate [(Fe

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

, Mn

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

)(Nb

Niobium

Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...

, Ta

Tantalum

Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...

)₂O

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

₆], is a black mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 group that is an ore of niobium

Niobium

Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...

 and tantalum

Tantalum

Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...

. It has a submetallic luster

Lustre (mineralogy)

Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....

 and a high density and is a niobate of iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 and manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, containing tantalate of iron. This mineral group was first found in Haddam

Haddam, Connecticut

Haddam is a town in Middlesex County, Connecticut, United States. The population was 7,157 at the 2000 census. The town was also home to the now decommissioned Connecticut Yankee Nuclear Reactor.-Geography:...

, USA. It forms a series with the tantalum

Tantalum

Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...

-dominant analogue ferrotantalite and one with the manganese-dominant analogue manganocolumbite. The iron-rich member of the columbite group is ferrocolumbite. Some tin and tungsten may be present in the mineral. Yttrocolumbite is the yttrium-rich columbite with the formula (Y,U,Fe)(Nb,Ta)O₄. It is a radioactive mineral found in Mozambique

Mozambique

Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...

.

Columbite has the same composition and crystal symmetry (orthorombic) as tantalite

Tantalite

Tantalite, [2O6], is a mineral group that is close to columbite. The two are often grouped together as a semi-singular mineral called coltan or "columbite-tantalite" in many mineral guides. However, tantalite has a much greater specific gravity than columbite...

. In fact, the two are often grouped together as a semi-singular mineral series called columbite-tantalite

Coltan

Coltan is the industrial name for columbite–tantalite, a dull black metallic mineral from which the elements niobium and tantalum are extracted. The niobium-dominant mineral is columbite, hence the "col" half of the term...

 or coltan in many mineral guides. However, tantalite has a much greater specific gravity

Specific gravity

Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 than columbite, more than 8.0 compared to columbite's 5.2.

Columbite is also very similar to tapiolite

Tapiolite

Tapiolite [2O6] is a black mineral that is an ore of niobium and tantalum. It has a submetallic luster and a high specific gravity and is a niobate of iron and manganese, containing tantalate of iron....

. Those minerals have same chemical composition but different crystal symmetry: orthorhombic for columbite and tetragonal for tapiolite. The largest documented single crystal of columbite consisted of plates 6 millimetre (0.236220472440945 in) thick measuring 76 by 61 cm (29.9 by 24 ).