More known by the public under the name of coltan. It is a black mineral whose content of rare elements, such as niobium and tantalum make it essential in the manufacture of electronic devices such as computers, mobile phones, consoles etc. The ownership of the African deposits of this mineral has provoked bloody wars to the point that it is attributed to have caused millions of deaths. Extremely dense and with an attractive metallic gloss it is rare to find it with well-shaped crystals in mineral collections.