Black Diamond Mines is a very popular park just outside Antioch. Old mines and the now-empty sites of mining towns are scattered throughout the park. The park has a nice mixture of oak woodlands and rolling grass-covered hills, with great views of Antioch and the surrounding hills.
While the park isn't excessively crowded, the Antioch/Brentwood area is one of the most rapidly-developing parts of the Bay Area and is now somewhat underserved with parks compared to more central locations. But the parks that it does have are among the best in the Diablo Range.
The park's main mining-related sight is the Hazel Atlas Mine. The open part of the mine is a long tunnel with an impressive series of chambers branching off of the end. Normally the mine can only be visited by taking a $5, 90-minute tour given at 12 noon and 3 pm. However, four times a year the park has open houses during which you can walk through the mine at any time for free. The Greathouse Visitor Center is in a smaller, but still pretty impressive, mine tunnel.
The park also has five old town sites. No sign of the towns remain; all that's left are rather unattractive patches of bare ground and piles of mine tailings.
* The Ridge Trail (5.4 mi, 980 ft)
This hike starts at the Frederickson Road trailhead, skirts the pastoral Lone Tree Valley, and climbs to a ridge with great views over Antioch.
* The Star Mine Trail (7.3 mi, 1560 ft)
From the very popular Somersville Road trailhead, this hike climbs to a ridge and descends into the vast, undeveloped Deer Valley.
© 2015 David Baselt