Mercury mines - once places prisoners were sent to die, now superfund sites? I had no idea San Francisco Bay had been poisoned by mercury from an upriver mine. The channel out front of my house up has a polluted layer full of mercury from the old gold mines. Plus cyanide in the soil near the old mill, still smelling of almonds if you dig down a few feet, as the sunlight has never been able to reach it and allow it to decompose. Arsenic and lead all over the place, too.

The Wikipedia article about mercury and vermilion is also an interesting read:

http://en.wikipedia.org/wiki/Vermilion