This PDF (i saw a translated version) has been brought to my attention.

it claims that Coltan is the main cause of a conflict which has claimed the lives of four million people since 1997 and as also caused the disappearance of several populations of gorillas.

The extraction of coltan, a very rare mineral used mainly for technological purposes, has led to a long internal conflict in Congo, that since 1997 (more than a decade ago), as claimed more than four million lives. The struggle to control the mines of this mineral, as well as the diamond mines, has led to this terrible situation, which as claimed many lives before the eyes of the international community. There have been and there still are real situations of famine in many regions of this country that supports an almost untenable external debt. However, Congo is one of the richest countries in the world, being "The basin of the Congo River”, the second largest rainforest on earth. In the mountains of Kakuzi‐Biega National Park, where Coltan is extracted, the lives of hundreds of gorillas are in danger or have finished this last decade, causing the loss of important groups of this endangered species, compromising its long term survival.