DIAMOND MINES REGIONAL PRESERVE
The Black Diamond name refers to the coal that was dug out of this area between 1860 and the early 1900's. Other industries occurred there until the 1970's when East Bay Regional Park district began acquiring land for a park. Remnants of the mines are still present and there is a unique Greathouse Visitors Center located under ground with natural history tours available. For hikers there are over 40 miles of hilly trails available through mainly Oak and grass woodlands.
Park Location: here
Trail Map: here
Park Page: here