By inducing and exacerbating landslides, mudflows and slope erosion and by releasing hazardous substances to the surroundings, the impact of these activities on the environment in general, and on water in particular, is considerable. The most important mineral deposits being exploited are gold, but also other minerals such as coal, mercury', uranium and antimony'. Coal output diminished from 2.5 million tons in 1992 to 0.4 million tons in 2003 and 0.3 million tons in 2006.