The San Cristóbal Tunnel was once part of one of the largest mercury mines in the world, second only to the Almaden mines in Spain. The network of tunnels was dubbed New Almaden, and generated more wealth than any gold mine in California.
The mercury, or ‘quicksilver’, of New Almaden was used heavily during the California Gold Rush to extract gold from mined ore, and for this reason the tunnels were eventually abandoned after the rush, although some continued activity until the 1970s.
The San Cristóbal Tunnel is one of the only remaining visible tunnels which hasn’t had its entrance filled in. The only way to see it is to hike 5 miles on dusty trails up into the San Jose hills.
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