From The Looting Machine: Warlords, Oligarchs, Corporations, Smugglers, and the Theft of Africa's Wealth, by Tom Burgis (PublicAffairs, 2016), Kindle p. 30:
The Congolese are consistently rated as the planet’s poorest people, significantly worse off than other destitute Africans. In the decade from 2000, the Congolese were the only nationality whose gross domestic product per capita, a rough measure of average incomes, was less than a dollar a day.
Tantalum’s extremely high melting point and conductivity mean that electronic components made from it can be much smaller than those made from other metals. It is because tantalum capacitors can be small that the designers of electronic gadgets have been able to make them ever more compact and, over the past couple of decades, ubiquitous.
Congo is not the only repository of tantalum-bearing ores. Campaigners and reporters perennially declare that eastern Congo holds 80 percent of known stocks, but the figure is without foundation. Based on what sketchy data there are, Michael Nest, the author of a study of coltan, calculates that Congo and surrounding countries have about 10 percent of known reserves of tantalum-bearing ores. The real figures might be much higher, given that reserves elsewhere have been much more comprehensively assessed. Nonetheless, Congo still ranks as the second-most important producer of tantalum ores, after Australia, accounting for what Nest estimates to be 20 percent of annual supplies. Depending on the vagaries of supply chains, if you have a PlayStation or a pacemaker, an iPod, a laptop, or a mobile phone, there is roughly a one-in-five chance that a tiny piece of eastern Congo is pulsing within it.
The insatiable demand for consumer electronics has exacted a terrible price. The coltan trade has helped fund local militias and foreign armies that have terrorized eastern Congo for two decades, turning what should be a paradise into a crucible of war.