The East Bay Regional Park District began acquiring land for Black Diamond Mines Regional Preserve in the early 1970s. Today, most of the mining district is within the Preserve's nearly 6,096 acres. The area is an ideal location for hiking, picnicking and nature study. Naturalists conduct a variety of programs relating the Preserve's natural and historic resources.
We hiked during Thanksgiving holiday weekend. The weather was perfect. After the rain all hills were green. The trails were damp but not muddy. The views were gorgeous. The hike was a mildly challenging and fun, it had two significant hills for a total ascent of 1800 feet along 7 miles. We hiked on the Chaparral Trail up to the Ridge Trail and then came down to the Stewartville Town site. We returned up the steep on the single track Miner's Trail that follows along a hill ridge back to the Ridge trail.
I truly enjoyed this beautiful place. We parked off of Frederickson in the parking area. There are no restrooms here, just a heads up. Ascending the Stewartville Trail, then winding left onto the Star Mine Trail at the camp area, you'll walk through the camp parking lot to continue. We went even further to the Oil Canyon Trail at Star Mine's end, to the upper Overlook, which is a fairly steep incline. It was lovely up there with a valley/delta view, but wires (and electrical noises) disrupt the view and sounds. Coming down, we hit the Stewartville Trail back, stopped to add Prospect Tunnel to our hike (+1.5 mi), then back to the parking area. The tunnel is great, you can walk inside, but I recommend a flashlight. There's a great variety of wildlife present throughout the preserve. Today, we spotted two coyotes from a pretty close distance at the summit of Star Mine.
From the parking lot and back, with all of the above, we timed at 4 hours exactly.
The trail goes through 3 different old mining sites and the Rose Hill Cemetery. It as some pretty good hills and is on the upper side of moderate. I did it in late march so there were some wildflowers starting to bloom. Very good winter and spring hike and probably a 3 1/2 stars for me.
Very little shade. You will be out in the sun for most of it. The cave is not a part of the highlighted trail. Make sure you take the detour to go see it. A good portion of the trail is walking along dirt roads. There is a lot of inclines but they lead to beautiful views of the rolling hills and parts of the surrounding city. Worth checking out. Bring extra water.