Also called niobite, niobite-tantalite and Columbite [(Fe, Mn)Nb2O6], is a black mineral group that is an ore of niobium.

It has a submetallic cluster 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 ferro tantalite and one with the manganese-dominant analogue mangano Columbite.

The iron-rich member of the Columbite group is ferro columbite. Some tin and tungsten may be present in the mineral. Yttrium Columbite is the yttrium-rich Columbite with the formula (Y,U,Fe)(Nb,Ta)O4. It is a radioactive mineral found in Mozambique.

Columbite has the same composition and crystal symmetry (orthorhombic) as tantalite. In fact, the two are often grouped together as a semi-singular mineral series called Columbite-tantalite or Coltan in many mineral guides. However, tantalite has a much greater specific gravity than Columbite, more than 8.0 compared to columbine’s 5.2.

Columbite is also very similar to tapiolite. 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 millimetres (0.24 in) thick measuring 76 by 61 centimetres (30 in × 24 in).

Tandem Lieber Holdings - Gold


Gold is a chemical element with symbol Au (from Latin: aurum) and atomic number 79. In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable and ductile metal. Chemically, gold is a transition metal and a group 11 element.

Tandem Lieber Holdings - Tantalite


The mineral group tantalite [(Fe, Mn)Ta2O6] is the primary source of the chemical element tantalum. It is chemically similar to Columbite, and the two are often grouped together as a semi-singular mineral called Coltan.

Tandem Lieber Holdings - Niobium


Niobium, formerly columbium, is a chemical element with symbol Nb (formerly Cb) and atomic number 41. It is a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and Columbite.