Group 12 element have zinc in its active site. In 1817, cadmium was discovered in Germany as an impurity in zinc carbonate minerals (calamine) by Friedrich Stromeyer and Karl Samuel Leberecht Hermann. It was named after the Latin "cadmia" for "calamine", a cadmium-bearing mixture of minerals, which was in turn named after the Greek mythological character, Κάδμος Cadmus, the founder of Thebes. Stromeyer eventually isolated cadmium metal by roasting and reduction of the sulfide. In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths). This definition has since
Coltan Coltan Coltan (short for columbite–tantalites and known industrially as tantalite) is a dull black metallic ore, from which the elements niobium and tantalum are extracted. The niobium-dominant mineral in coltan is columbite (after niobium's original American name "columbium"), and the tantalum-dominant mineral is tantalite. Tantalum from coltan is used to manufacture batteries for electric cars, and in tantalum capacitors it is used in electronic products. Coltan mining has helped to finance serious conflict in the Democratic Republic of Congo, for example the Ituri conflict and the Second Congo War. Approximately 71% of global tantalum supply in 2008 was newly mined,