The mines in the preserve produced over four million tons of coal between the 1860s and early 1900s.
Sand mining occurred at the site from the 1920s to the 1940s to support the glass-making industry in the San Francisco Bay Area.
The Rose Hill Cemetery within the park is the oldest Protestant cemetery in Contra Costa County.
Subterranean mine temperatures remain constant year-round, typically hovering around 58 degrees Fahrenheit.
The park's name originates from the specific type of coal extracted, known as 'black diamond' or sub-bituminous coal.
More than 30 miles of trails are available for public use, ranging from easy loop walks to strenuous ridge climbs.
Black Diamond Mines Regional Preserve is a 6,000-acre park encompassing the remnants of five 19th-century coal and sand mining towns, including Somersville and Stewartville. The landscape features rugged terrain, oak woodlands, and open grasslands typical of the East Bay hills. Visitors can explore the underground Greathouse Visitor Center, which provides access to a subterranean mining museum. Several miles of hiking, biking, and equestrian trails traverse the preserve, connecting to the regional Diablo Foothills. The park contains a historic cemetery where miners and their families were interred between 1864 and 1928. Wildlife sightings commonly include coyotes, bobcats, and golden eagles. The area's unique geology includes fossil-bearing sandstone layers from the Eocene epoch.
The view from the top of the Manhattan Canyon trail, which offers panoramic vistas of the Sacramento-San Joaquin River Delta.
Bring a light jacket, as the underground mine temperatures are significantly cooler than the surface, especially during summer.
Check the official East Bay Regional Park District website for guided tour availability before arriving, as mine entry is often restricted to scheduled programs.
Wear sturdy, closed-toe hiking boots, as the trails are often steep, rocky, and uneven.
Attempting to hike during the peak heat of summer afternoons without adequate water and sun protection.
The visitor center and mine tours operate on a seasonal schedule and are typically closed on certain weekdays; check the official park district website for current operating days.
Stay on marked trails to protect sensitive habitat and avoid entering closed mining shafts for safety and historical preservation.
