Striking view of the New Almaden Mine and Mills, from Thomson & West's Historical atlas map of Santa Clara County, California. Compiled, drawn and published from personal examinations and surveys by Thompson & West, San Francisco.
The New Almaden quicksilver mine in the Santa Teresa Hills in Santa Clara County is the oldest and most productive quicksilver (mercury) mine in the U.S. The site was known to the Ohlone Indians for its cinnabar long before a Mexican settler discovered the ores in 1820. By the time they were identified as mercury, the mine was perfectly timed to supply the California Gold Rush. The mine ran intermittently after 1927 and eventually closed.