
We knew we were getting close when the signs by the river warned of contaminated fish.
After a brutal uphill grunt, we found miles of wonderful trails, and the entrance to the New Almaden mercury mines – 100 miles of tunnels in total.
The mining began in 1845 when Mexican Cavalry Captain Castillero discovered that the red rock used by the local Ohlone Indians to paint their faces and the walls of the Santa Clara Mission was cinnabar, an ore of mercury and sulfur. They needed mercury to process silver in the Mexican silver mines.
This mercury mine produced more fortune than any Californian gold mine in history… despite the “gold rush” marketing.
To separate gold or silver from crushed ore, they used mercury.

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