OverviewBlackcap Mountain is an apt name for this peak in the Pasayten Wilderness. It does indeed have a top section that appears as a black cap--especially when viewed from the east or southeast. The rocks that comprise the "cap" are black hornfels. The rock below the cap are mostly pink granite porphyry. Blackcap is a rugged peak closely linked with higher Monument Peak to the south. Blackcap Mountain is approximately the 79th-highest peak in the state but it is overshadowed by five higher neighbors in Osceola Peak, Mt. Carru, Mt. Lago, Lost Peak, and Monument Peak. Because of its positioning, however, it affords excellent views of all of these higher peaks.
Getting ThereThe Pasayten Wilderness is generally not as rugged as other regions of the Cascades to the west and southwest, but the terrain around Blackcap Mountain is quite rugged. There are two standard approaches to the peak. The easiest approach, though not necessarily shortest, would be from 6,960-ft Slate Pass on Harts Pass Road. For this approach, you want to descend from Slate Pass to the Robinson Creek Trail No. 478 as it parallels the Middle Fork Pasayten Wilderness, head up to Freds Pass at Berk Creek, then cross to the head of Eureka Creek immediately NNE of Blackcap. The second approach (to the east side of Blackcap) would be via Monument Creek Trail to a point maybe three miles before Butte Pass where Monument Creek turns west to a head in the Monument-Blackcap basin. This basin is open and pleasant once you get to its upper section by either going up to the left or right of the bisecting cliffband.
Red TapePermits are not required as far as I know, though signing a trailhead register might be requested. When I was out there for a week in August, I saw less than five people once I got back to the Shellrock Pass vicinity. You'll see more people (and horses and dogs) on the Robinson Creek Trail, which runs along the Middle Fork Pasayten River north of Slate Pass.
When To ClimbThe peak could probably be climbed in every season except winter. Access depends on conditions for getting to the trailhead. The Slate Pass trailhead is ~6,900 ft up. In fact, the road to Slate Peak Lookout is the highest well-traveled road in Washington. Harts Pass Road is also one of the more exposed roads to drive on. Combine that with the many sightseers who use the road and it becomes a concentrating endeavor. The snowier the approach, the longer time you'll need to get in and out. The peak will probably require three days to get to, climb, and get back from, so plan accordingly. If doing the climb from Shellrock Pass or from the basin east of the summit, technical equipment will probably not be necessary. The East Ridge scramble from the saddle is mostly only class 3 but there is some exposure on loose rocks near the top (on the black cap part of Blackcap). In early season, an ice-axe is probably advisable.
CampingThere are numerous campsites. Some I know of are:
1. At or near the horse camp where the Ferguson Lake Trail junctions off from the Robinson Creek Trail
2. At the intersection of the Robinson Creek Trail and Berk Creek (this is where the trail up to Freds Lake, Freds Pass, and Lake Doris begins)
3. At Freds Lake
4. At Lake Doris
5. At the eastern head of Eureka Creek immediately south of Mt. Lago
6. At a half-acre sized bench at ~7,500 ft just southwest of Shellrock Pass. This is where I camped for five days. It is a good staging area for climbing all the peaks in the region. There may or may not be a snowpatch there for water. Bring a filter.
7. In the basin east of Blackcap Mountain (grassy terraces but a marmot metropolis)
Mountain ConditionsWhen I was in there in August 2001, I was snowed on lightly for one night at my 7,500-ft camp. Knowing this, plan your clothing appropriately. It can be hot or cold or in between in the Pasayten. Ordinarily, you won't get much rainfall as the wilderness is far east of the Cascade Crest. However, when I was there, it rained for 36 hours straight. I stayed in my tent nearly the whole time.