Cadmium in Germany, as an impurity in zinc carbonate. Stromeyer found the new element as an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, because it was found in this zinc ore. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by roasting and reducing the sulfide. The potential for cadmium yellow as pigment was recognized in the 1840s, but the
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,