Mining gold, ruining rivers in Kalimantan

Mining involves a dredge that raises sand from the river bed and another that sprays the sand to separate impurities from gold-bearing grains. With the aid of mercury, which is poisonous, the grains are amalgamated.
 Here contamination sets in, as the mercury is later dumped into the river.

Grains contain different grades of gold, which determine their prices. So-called pure gold, with a purity of 99.9 percent, costs about Rp 500,000 per gram.

The higher the grade is, the more reddish-yellow its appearance. Conversely, lower-grade gold is dull yellow and sells for less.

The wildcat miners face arrest by law-enforcement officials and dangerous working conditions due to a lack of standard security equipment.
http://www.thejakartapost.com/news/2013/09/24/mining-gold-ruining-rivers-kalimantan.html