Of course, I have been meaning to quote it a bit here. Now that I finally started punching my keyboard, the first thing I see is someone else did already. Of course. Check out mongabay.com / High mineral prices drive rainforest destruction by Rhett A. Butler and the selection of back posts they link to below the main text. Also, someone put the actual article online - don't know if it's alright copyright wise but it's there (PDF).
The short, short version: Mineral prices are up, incentive to mine follow. 3rd world countries struggle to (or give up) handle the pollution, illegal miners, conflicts with indigenous people etc. etc.
As miners move into remote areas, lawlessness, prostitution and armed clashes often follow
Mining is also something Jared Diamond writes about in his latest master piece Collapse: How Societies Choose to Fail Or Succeed, a book everyone not wanting to help destroy our habitable biosphere should consider reading. It's chapter 15: Big businesses and the environment: Different conditions, different outcomes (pages 452-468 in my edition).