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). When 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. 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. A few steps later, 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 on the right, Stewartville Trail begins to climb. The trailside grassland hosts owl's clover, fiddlenecks, and ithuriel's spear in spring. At about 0.7 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 peek 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. Later 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, 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. When 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 1.4 miles, Ridge Trail ends at a signed junction. Continue straight on Chaparral Loop Trail.
     To the west, past a low-slung sandy knoll, a prominent reeflike hill rises, with rocks jutting out at an angle. The trail rises to a power tower, then begins a descent. A few stretches are aromatic alleys, with sweet smells wafting from manzanita blossoms (winter), black sage and pitcher sage flowers (spring), and a froth of chamise blooms (summer). A few live oaks mingle with pine and yerba santa as the Chaparral Loop Trail drops on steps and some steep grades into Manhattan Canyon. In mid-May, I have seen dozens of fairy lanterns blooming along the trail. Just after a bridge crosses the canyon at 1.8 miles, you’ll reach a junction, with the trail to the right closing the Chaparral Loop. Turn left, following the sign toward Manhattan Canyon Trail. After a brief, winding climb through chamise and six-foot-tall manzanitas, there’s a second junction. Manhattan Canyon Trail, to the right, leads first uphill, then downhill back toward the trailhead. Turn left onto Manhattan Canyon Trail.
     On a slope just uphill from the canyon floor, the narrow trail ascends through live oaks, pine, sticky monkeyflower, toyon, and manzanita. Somewhat abruptly, the canyon widens into a grassy bowl near the park boundary. Blue oaks dot the hillsides as the Manhattan Canyon Trail veers right and climbs steeply, ending at a junction with Black Diamond Trail at 2.15 miles. A bench to the right just before the junction is a good place to catch your breath. Turn right onto Black Diamond Trail.
     Trailside vegetation is a mixture of grassland, pine, manzanita, and blue and live oaks. Look off to the right for views back to Chaparral Loop and Ridge trails. After a brief level interlude, the fire road begins to descend easily into chaparral, where you might see ceanothus, black sage, yerba santa, chamise, and pitcher sage. At 2.35 miles, the connector to the Manhattan Canyon Trail departs on the right. Continue straight on Black Diamond Trail, ascending at a moderate grade back into grassland. On the far side of a cattle gate beneath a power tower, there are sweeping views to Stewartville Trail. By mid-May, the tips of high hills rising up to the northeast begin to fade from green to dull brown, drained of color. In early spring, shooting stars bloom in staggering numbers along the trail, in the grassy breaks between clusters of blue and live oaks. Black Diamond Trail begins to descend easily, offering views northwest to Suisun Bay on clear days. At 2.9 miles, Black Diamond Trail ends at a junction with Nortonville Trail. Turn right.      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 3.3 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 3.35 miles, encounters the second leg of Manhattan Canyon Trail. Continue straight.
      Red winged blackbirds are plentiful here, especially on the left side of the trail in a marshy area. Descending at a gentle pace, the trail reaches a signed junction at 3.6 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: 3.7 miles
Last hiked: Tuesday, March 27, 2001