Three 3T’s and G
The minerals, mined by hand from workers with no training or special tools, do not look like the stylized metallic of the latest smartphone. Each mineral, with the exception of gold, is a grey-blue color, which when covered with dirt or other rock, can make identification difficult.
Tantalum, which has received the majority of attention in the conflict and which will occupy most the discussion in this website, is used to store the electricity in cell phones and other electronics. Discovered in 1802, it was not until the 1940s that tantalum became a key component in the production of electronic capacitors of radar and military radio communications.
When the metal on your gadget is heated using an electrical charge, circuits can break down if they overheat. But tantalum easily releases its heat, allowing the circuitry in cell phones and electronics to function smoothly. It’s also highly ductile, allowing for easy welding. As a component, it can be found in circuits in mobile telephones, laptop computers, airbag protection systems, video game consoles, video cameras and digital cameras.
The Democratic Republic of Congo is said to hold approximately 60 percent of the world’s tantalum reserves. But currently, they contribute approximately 15 percent of the worldwide market, with Brazil and China accounting for approximately 15 percent and 8percent respectively. The continent of Africa as a whole, however, accounts for approximately 30percent of global supply, with a significant portion of that thought to have originated, and been smuggled from the DRC.
Tungsten, discovered in 1781 and known for its high melting point, is used, among other things, to construct light bulbs and laptop screens and to make cell phones—such as Blackberries–vibrate. Because of its ability to retain its strength at high temperatures, it’s also used for rocket nozzles and integrated circuits. 
Tin, produced from casserite ore, is essential for the production of solder on circuit boards, tincans, and for coating the metals of other electronic equipment. Because it is not easily oxidized, also prevents corrosion.
Whereas tantalum has largely been the face of the conflict, DRC tin has recently stepped into the spotlight as Congolese villagers and rival militias try to take advantage of its rising price. Japan and the European Union banned the use of lead-based solder for electronics in 2002,thus making tin the mineral of choice for soldering.
Gold, which is an efficient conductor of electricity and which also does not corrode easily, is used to coat the wires in nearly all cell phones and many other electronic devices.