Mercury used to be easy to get, now it's treated like plutonium. The problem is it's used in low-tech gold mining: if a mercury atom meets a gold atom WHAM they stick together. Mercury and gold stuck together are amazingly heavy. So you powderize the ore, mix in some mercury, powderize it some more, then wash all the lighter dirt off (along with quite a bit of mercury that goes staright into the nearest river) - you're left with a bit of mercury/gold amalgam. Then you just heat that in a big steel pit and boil the mercury off: a simple condenser collects some mercury for re-use. What's left is pretty pure gold.
Nobody in their right mind does this any more, and many rivers in the US west are hopelessly polluted with mercury from mining done many decades ago. The fumes are also a pwerful neurotoxin - the mad hatter along with a bunch of mad miners.
Nobody is claiming that Brazilian peasants are in their right minds though. They have a chance to make a few bucks doing backwoods mining for gold in the Amazon basin. They need mercury for that. An international trade has developed getting mercury from anywhere possible to sell to these guys. The civilized world, after polluting their (our?) rivers with mercury, thinks Brazilians shouldn't be allowed to pollute theirs. So mercury is really hard to get legally - trade in the US and Canada is restricted to approved users only.
Try asking at any place that deals in or fixes old clocks. Mercury was used quite often as a weight in clock pendulums in "grandfather" and mantel clocks. Usually one replaces the bottle of mercury with a lump of lead because of the health hazard.
I tried to get some at a recycling centre. They had a big bin full of old thermostats. The reaction was what I would expect if I went to a farm supply store and tried to buy a ton of ammonium phosphate! They wouldn't give or sell it to me and wanted some identification... probably to send the mercury police to see me or maybe just a hazmat team to demolish my house on suspicion of mercury contamination.
