You might not know it from the textbooks, but California's gold rush was also a mercury rush. Quicksilver mines near San Jose provided gold miners with the mercury they needed to separate gold from ore. 150 years later, we're still facing the consequences of gold-rush era mercury, much of which is lodged in the Bay's mud and in its fish.
Historical mercury mining photos courtesy of the New Almaden Mining Museum, with special thanks to Art Boudreault.