The _usual_ natural form of mercury is cinnabar (Mercury Sulphide) a rather pretty mineral.
Linkage -http://mineral.galleries.com/minerals/sulfides/cinnabar/cinnabar.htm
However, Mercury is
weird and can form its liquid state naturally.
Of course, mercury (especially the methyl-mercury compounds) are toxic in the extreme, this enhanced by it's stability and dammable persistance in the ecosystem.
It's found in many parts of the world (Funnily enough) but I though tthis could be of use to those planning a run:
http://pubs.usgs.gov/fs/fs-0072-94/Nothing like finding a mine that's producing naturally-radical mercury to make your day...and then the problems set in. I mean, it's HEAVY - many liquid-designed containers can't handle the density and break/burst.
And why is it there? Admittedly, mercury-bearing cinnabar isn't rare, but for liquid radical mercury?
I'd be looking around for a toxic Enchanter. Oh - and it's rather easy to extract mercury from the cinnabar matrix - usually crushing and then heating in a vacuum works very well, Hg vapourises easily.
However, this is fraught with dangers, especially if the extraction area is actually open (Traditionally done for thousands of years.) and not vented properly.
You'd be amazed at how many of you could do this stuff in your kitchen - just becuase it's more profitable to do it in a large steel mill, etc, doesn't mean you're incapable of alchemy in the back yard.
Unless you're trying to extract aluminium, that is.
L;
No, I'm not a Geologist, I'm a Food Scientist.
pH33r my L33t f00d Sk1LLz!