columbitegroup

The columbite group is a group of minerals that are isostructural with columbite, (Fe,Mn)Nb2O6. The group includes columbite-(Fe), columbite-(Mn), tantalite-(Fe), and tantalite-(Mn). These minerals are oxides of niobium and tantalum, with iron and manganese as the dominant cations. The group is named after columbite, which was first described in 1801 from the Ilmen Mountains in Russia. The name columbite is derived from the Latin word "columbium," which was the old name for niobium.

The columbite group minerals are typically black or dark brown in color and have a metallic luster. They are often found in granitic pegmatites and in hydrothermal veins. The minerals are used as sources of niobium and tantalum, which are important in the production of superconductors, capacitors, and other electronic components. The group is also of interest to mineral collectors due to its distinctive crystal forms and colors.

The columbite group minerals are characterized by their high specific gravity, typically ranging from 5.2 to 6.0. They are also known for their strong pleochroism, which is the property of a mineral to absorb light of different colors to different degrees. This property is often used to identify the minerals in the group. The minerals are also known for their high refractive index, which is a measure of how much light is bent when it passes through the mineral.

In summary, the columbite group is a group of minerals that are isostructural with columbite and are used as sources of niobium and tantalum. The group includes columbite-(Fe), columbite-(Mn), tantalite-(Fe), and tantalite-(Mn). The minerals are typically black or dark brown in color and have a metallic luster. They are often found in granitic pegmatites and in hydrothermal veins. The group is also of interest to mineral collectors due to its distinctive crystal forms and colors.