Brazil Gold Mining : The BRAGOLD Case

The actual dispute is over the effects of the gold mining
process on the Amazon, specifically the mercury used to isolate
the gold from the surrounding sediment.  The amount of mercury
entering the environment from gold mining activities is estimated
to be 200 tons last year alone.  Mercury enters the environment
during each of the two steps involved in acquiring the gold.
First, the sediments are taken from river bottoms and land mining
sites and forced through a number of sieves.  The sieves are
coated with mercury, which bonds with the gold in the sediment
separating it from the rest of the material.  Obviously,
considerable amounts of mercury are left in the gold depleted
soil and enters the environment when this material is discarded.
Second, the gold-mercury amalgam is heated to purify the gold by
vaporizing the mercury.  If the heating is done in an unsealed
container, it enters the environment in gaseous form.  This is
particularly dangerous to the miner or smelter purifying the
gold, as the person invariably inhales the mercury through
breathing.  Experts say that for every pound of gold produced
a corresponding two pounds of mercury enters the environment.
http://insomnia.pinguinland.eu/2013/01/04/brazil-gold-mining-the-bragold-case/