South San Jose's biggest park is also one of the Bay Area's most unusual industrial history sites. For 135 years, the hills of Almaden Quicksilver County Park were mined for mercury. Today the old mining roads are trails.

The mines

The park is named for the New Almaden Quicksilver Mines, which were in turn named for the famous mercury mine at Almadén, Spain. According to Wikipedia, the mines operated from 1847 to 1976. They were crucial during the Gold Rush because mercury was used to pull gold out of ore. By the time Santa Clara County bought the property in 1976 and ended operations, the mines had produced 83,974,076 pounds of mercury, worth more than $70 million.

Remains of mining-era structures are scattered through the park. They once housed up to 1,800 miners. The biggest cluster is at English Camp, set up by Cornish miners in the 1860s. There's also a memorial to Civilian Conservation Corps firefighters once stationed there. The Casa Grande Almaden Quicksilver Mining Museum is nearby in the village of New Almaden.

The trails

The park has about 37 miles of hiking trails. Thirty miles are open to horses and 16.6 miles to bikes, according to an independent guide to the park. Many trails pass old mine shafts and furnace sites. The guide warns that "there are virtually no flat trails in the park." Most trails climb or drop at least a few hundred feet per mile. The park sits on Los Capitancillos Ridge, between the flat Almaden Valley and the higher Sierra Azul range, home of Mount Umunhum. Elevations range from under 600 feet at the main eastern entrances to more than 1,700 feet at the top. The ridge trails have views across San Jose.

Know before you go

  • Entrances: There are five. The most popular is the McAbee entrance off Camden Avenue.
  • No visitor center: Information is available at the Casa Grande on New Almaden Road, near the Hacienda entrance.
  • Bring water and a map: The guide recommends carrying water, snacks and a map, or knowing your route, because of all the climbing.
  • Don't eat the fish: The park includes Guadalupe Reservoir, and Almaden Reservoir is next door. See why the mercury legacy means you shouldn't eat fish from those reservoirs.

The county opened Almaden Quicksilver during a late-1970s park-building push that also produced Grant Ranch and Sanborn county parks, according to Wikipedia.