[This PDF][1] (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.


  [1]: http://www.simiomobile.com/downloads/coltan_deadly_ore_eng.pdf