Black Diamond Mines Regional Preserve,
East Bay Regional Park District,
Contra Costa County
In brief:
3.5 mile loop through grassland and chaparral, at a preserve which was a former coal mine.

Distance, category, and difficulty
This 3.5 mile loop hike is on the moderate side of easy. Trailhead elevation is about 740 feet. The featured hike climbs to about 1250 feet, then descends back to the trailhead. Total elevation change is about 700 feet.

Mostly exposed, with some shade.

Trail traffic

Trail surfaces
Dirt fire roads and trails.

Hiking time
2 hours.

Too hot in summer. Best in late winter and early spring.

Getting there:
• From CA 4 in Contra Costa County exit Somersville Road (exit 26a eastbound/26 westbound). Drive south on Somersville to the park entrance.
• If you're driving from San Francisco, or the south bay, these directions may make your trip quicker (or at least more pleasant): from the CA 24/Interstate 680 interchange in Contra Costa County, exit Ygnacio Valley Road (exit 46b). Drive east on Ygnacio Valley Road about 8 miles, then the road changes into Kirker Pass. Continue about 5 miles on Kirker Pass to the junction with Buchanan. Turn right and drive about 3 miles to Somersville Road. Turn right and drive to the park entrance.

Get driving or public transit directions from Transit and Trails:

GPS Coordinates* for Trailhead:
Latitude 3757'30.00"N
(* based on Google Earth data, shown as degrees, minutes, seconds)

Gas, food, and lodging:
Gas, stores, and restaurants back on Buchanan. Camping info from EBRPD: "There are two camping areas in Black Diamond Mines Regional Preserve. Reservations are required for both--call (510) 562-2267. Neither camping area has water, so water must be transported in. Star Mine Group Camp Area, available during spring, summer and fall, is for organized, educational groups only. It can accommodate up to 40 people. It is located in a grassland/oak woodland community at the eastern edge of the Preserve. Overnight camping is limited to two nights. Parking (maximum eight cars), picnic tables and a pit toilet are available at the site. Campers must bring in their own water and haul out their own garbage. Stewartville Backpack Camp is for the general public. The fee is $5 per night per person. Camping is limited to two nights during the spring, summer and fall. There is room for 20 campers. Picnic tables and a pit toilet are available, as well as water for horses (not for human consumption). The camp is located 3.2 miles from the Preserve headquarters, near the Stewartville and Upper Oil Canyon trails."

Trailhead details
Once inside the park, you can stop at the park office for a map or help with planning a hike. Then get back into your car and drive to the trailhead at the end of the road. Entrance fee of $5 charged when entrance kiosk is staffed. $2 dog fee. Drinking water, maps, and pit toilets at trailhead. Large parking lot. Emergency phone at park office. There is a designated handicapped parking spot, but trails aren't wheelchair accessible. There is no direct public transportation to the park, but you can walk (or cycle) to the trailhead from the Tri Delta Transit route 390 bus stop: visit the Tri Delta Transit website for details.

Most trails are open to hikers, equestrians, and cyclists, but a few trails are designated hiking-only. Dogs are permitted. Park is open from 8 a.m. to dusk.

The Official Story:
EBRPD's Black Diamond Mines page.
Park headquarters 925-757-2620

Map/Book Choices
A slight variation of this hike is described and mapped in 60 Hikes within 60 Miles: San Francisco, by Jane Huber (yup, that's me, the creator of this website). Order this book from
Map from EBRPD
Afoot and Afield: San Francisco Bay Area, by David Weintraub (order this book from has a great map and descriptions of a Black Diamond Mines hike.
• David Weintraub's East Bay Trails has a good map and descriptions of 3 Black Diamond Mines hikes (order this book from
• Geology Trails of Northern California, by Robin C. Johnson and Dot Lofstrom (order this book from has a nice geological description of this preserve.

View photos from the featured hike

Go to Bay Area Hiker Home page

Black Diamond Mines Regional Park was, once upon a time, ranch land like much of the east bay (of course, before that it was populated with Native Americans). Parking lotWhen in the 1860s coal was discovered at this parcel of land just south of Pittsburg, extensive mining took place, with nearly 4 million tons of "black diamond" removed from the earth. When coal use dropped off around the turn of the century, the land was mined for sand. More than 1.8 million tons of the stuff was removed. In spite of all that has been taken away, Black Diamond Mines is remarkable for what remains. An over 5,000 acre park, Black Diamond Mines boosts 65 miles of trails through grassland, chaparral, and oak savannah, and past sandstone rock formations. If one day at Black Diamond Mines isn't enough, a backpack and separate group camp make it possible to linger a little longer.
     Spring is the optimal time of year for a visit, although the blue oaks are lovely in autumn, and the manzanitas are stunning in winter. Springtime brings carpets of flowers, fresh oak leaves, and soft warm temperatures. Stewartville Trail If you wish to learn more about the mining history of Black Diamond Mines, you can stop by the Underground Mining Museum, and/or hike to the remains of the mines. Most mine entrances are barred, but bring a flashlight to explore 200 feet of Prospect Tunnel's 400-foot passage. If you're just interested in the trails, you'll have plenty to choose from. Short loops originate at the main trailhead, as well as the park office trailhead, and the entrance at Contra Loma Regional Park. Longer hikes of 8-10 miles are possible as well. If you visit once and are hooked like me, you'll have lots of map fun planning your next hike at Black Diamond Mines.
     Start at the gate near the information signboard at the end of the parking lot. Walk uphill on the broad multi-use Nortonville Trail.At about 250 feet, the trail crests at a signed junction. Turn left on Stewartville Trail, open to hikers, equestrians, and cyclists. Ridge TrailA few steps later, at about 0.16 mile, you'll reach a signed junction with Railroad Bed Trail. Continue straight on Stewartville Trail. The grade is initially level, but after passing a junction with the Pittsburg Mine Trail, Stewartville Trail begins to climb. The trailside grassland hosts owl's clover, fiddlenecks, and ithuriel's spear in spring. At about 0.55 mile, Stewartville Trail attains its peak elevation and reaches a signed junction just before a cattle gate. Turn right on Ridge Trail.
      Ridge Trail starts out open to equestrians, cyclists, and hikers, but a sign warns that there's no outlet for horses and bikes ahead, as the trail enters a sensitive ecological area where only hikers are permitted. There are nice views down into the valley to the southeast, and a peak at Mount Diablo to the west. Ridge Trail climbs for a few feet, then dips down and contours levelly around a hill. If you're hiking in late winter, you'll likely see Padre's shooting stars nestled in the grass. View from Ridge Trail down into the valleyLater in spring, lupines, buttercups, and fiddlenecks are plentiful. Buckeyes and blue oaks pepper the hillsides. On the left of the trail, look for the delicate white blossoms of woodland star in spring. On a clear day, views unfold to the right, permitting you to see all the way past the bay to Solano County. Ridge Trail begin to climb, and passes through a cattle gate. Look on the left for lots of bluedicks and a few owl's clover in early spring. Continuing to ascend, you might notice a change in the trailside vegetation. Oaks are still present, but the manzanitas seem out of place. And these aren't stunted shrubs, but full-size and even tree-size specimens. This shift in vegetation continues, and you'll reach a hilltop, at about 1195 feet, with more manzanitas and coulter pines. Also look for yerba santa and stunning red paintbrush blooming in early spring. On the left, a bare sandstone ledge provides the perfect rest stop. The view down into the valley is just incredible. This has to be one of my favorite bay area vistas. A verdant valley is dotted with ponds, and sheltered on both sides by hills. Chaparral lines the slopes on the west, while the eastern hills are shaded by oaks. A longer view to the west reveals the high peaks of Mount Diablo. When I visited on a breezy spring day, the winds rustled through the coulter pines, and I felt very far area from the bay area. Rock formation at the junction of Chaparral Loop and Lower ChaparralWhen you're ready, continue on Ridge Trail, which begins to descend. The flowers of winter's Indian warrior give way to the cheerful yellow blossoms of bush poppy as spring rolls around. Ridge Trail curves to the left away from a dropoff, revealing sandstone rock formations down the hill. At 1.25 miles, Ridge Trail ends at a signed junction. Turn right on Chaparral Loop Trail. (Option: if you want to avoid a descent followed by an ascent, and the crowds around the park's mining museum, you can continue straight at this junction, on Chaparral Loop. The mileage will be about the same, but you'll save yourself some energy.)
     Sandstone soil, fostering coulter pines, chamise, and manzanita, make this area of the park distinctive. Chaparral Loop Trail, a hiking only path, descends gently toward a rock formation. Paintbrush and bush poppy add color to the bare ground. At 1.32 miles, you'll reach a signed junction in front of the rock formation (as far as I know it is nameless, though it certainly deserves a great moniker). Bear left on Lower Chaparral Trail. Approaching Black Diamond Trail
     Lower Chaparral Trail is also closed to cyclists and horses. The sandy path loses elevation at an easy pace, then narrows and drops somewhat steeply through a very rocky stretch. After passing a path breaking off to the right (not a sanctioned route), Lower Chaparral Trail edges across a grassy hillside. Look on the left for royal larkspur, woodland star, and branched phacelia. Poison oak, which had been absent until this part of the hike, makes an appearance. Lower Chaparral Trail darts into the shade of coulter pines and manzanita, and ends at a signed junction at 1.59 miles. Bear left on Chaparral Loop.
     Hiking-only Chaparral Loop climbs on a narrow path through coulter pine, oaks, and manzanita. You'll pass rough paths that ascend to join Chaparral Loop from the creekbed on the right. At 1.89 miles, Chaparral Loop Trail meets a signed junction. Bear right (sign reads "to Manhattan Canyon Trail"). After climbing a few feet, you'll reach another junction, with Manhattan Canyon Trail. Turn right.Black Diamond Trail
     Buckbrush and chamise line the hiking only trail as it climbs. Look to the right, across the canyon, for views of more rock formations barely concealed by vegetation. At 1.96 miles, there is yet another junction. Manhattan Canyon Trail continues to the right, but turn left, "to Black Diamond Trail." (By the way, the last three junctions are really hard to follow with the park's map. It's worthwhile to write down these directions, or at least be prepared to roll with the punches if you find yourself off course.)
     The narrow hiking only trail skirts the base of a natural rock wall, through chamise, yerba Santa, sagebrush, and black sage. In spring you may see mosquito bills blooming in the shade on the right side of the trail, and fremont's camas tucked under the shrubs. There are nice views back across the canyon to the southeast, and you may even catch a glimpse of some steps on Chaparral Loop Trail. At 2.16 miles, the path ends at a signed junction with Black Diamond Trail. Turn right.View from Nortonville Trail
     After a short steep climb on multi-use Black Diamond Trail you'll leave chaparral behind, and enter a lovely oak savannah. In spring, look for carpets of bluedicks (they blend into the grass, so they aren't all that obvious considering their numbers). Black Diamond Trail levels out at a gate, and continues on a mostly flat course. There are long views, encompassing the journey so far, and through a notch near Rose Hill to the bay. If you're hiking in late winter, look to the right for a staggering display of Padre's shooting stars. These white flowers really stand out in the green grass. Black Diamond Trail begins to descend, passing under power lines and ending at a signed junction at 2.69 miles. Bear right onto Nortonville Trail.Nortonville Trail
      Nortonville Trail, open to hikers, equestrians, and cyclists, descends through grassland. Look for owl's clover, redmaids, and lupines in the spring. A path to the left departs to visit Rose Hill Cemetery, an optional side trip. At 3.17 miles, you'll reach a signed junction with one of the legs of Manhattan Canyon Trail. Continue straight. Nortonville Trail passes through a cattle gate, and at 3.31 miles, encounters the second leg of Manhattan Canyon Trail. Continue straight.
      Red winged blackbirds are plentiful especially on the left side of the trail in a marshy area. Descending at a gentle pace, the trail reaches a signed junction at 3.41 miles, with the most commonly visited area of the park, the Underground Mining Museum (another optional side trip). Continue straight on Nortonville Trail, under a few blue oaks, past the previously encountered junction with Stewardville Trail, and return to the trailhead.

Total distance: 3.5 miles
Last hiked: Tuesday, March 27, 2001