Why is large-scale mining a human rights issue in Colombia?

There is an excellent overview of the risks of large-scale mining in Colombia published yesterday on Colombia Reports. 

via CANADA-ALC, by Diego Melo, Colombia Reports, October 17, 2013
During the past four Colombian administrations, mining gold, coal and other minerals in high-demand seems to have been the solution to this paradox. In fact, these governments have decided to go deep into the land to extract that richness and turn it into wealth so as to compensate for what is missing on the surface.
By the end of 2012, mineral extraction took over 1,8% of the Colombian national territory[1], while 35% of the total landmass was promised as a potential mining site. That is, over a third of the country could host what governmental reports call “strategic investment areas.”