The next time we whip out our Blackberries, cell phones, gaming consoles, iPods, and laptops, we would do well to remember their true cost, beyond what we paid for them at the store. Each of these gadgets use an ore called coltan. About 80% of the world supplies of coltan lie in the Democratic Republic of the Congo, which the UN says is subject to "highly organized and systematic exploitation."

Coltan is "the colloquial African name for columbite-tantalite, a metallic ore used to produce the elements niobium and tantalum. In appearance, coltan is a dull black mineral. The exportation of coltan helped fuel the war in the Congo, a conflict that has resulted in approx. 3.8 million deaths." [Wikipedia]

In a country the size of Western Europe, a war rages that has lasted eight years and cost four million lives. Rival militias inflict appalling suffering on the civilian population, and what passes for political leadership is powerless to stop it. This is Congo, and the reason for the conflict - control of minerals essential to the electronic gadgetry on which the developed world depends - is what makes our blindness to the horror doubly shaming. Johann Hari reports from the killing fields of central Africa.