Columbite-tantalite or coltan is a mineral that has become of great importance to the world because its properties have been used in our cell phones, computers, aircraft engine blades, land-based gas turbines , grinding products for sputtering targets and chemicals for audio and video. This has increased the price of the black mineral and created a profitable business where tantalite is found in countries such as the Democratic Republic of Congo where the precious rock is found on the surface easy for its extraction. This process is often carried out by artisanal miners under guerrilla orders, so the next step in the supply chain after its extraction is the trading and processing of Coltan. Coltan is usually marketed in three forms: as ore concentrate, as tantalum oxides and salt, or as tantalum for capacitors. Columbite-tantalite is not traded on the stock exchange but in negotiations that take place on a bilateral basis between buyers and sellers around the world. Prices are discussed in private and purchase contracts between buyer and seller are almost secret. Traders a...