Pucaraju Colmillo Negro. From the trekking pass of Alto de Pucaraju, this free-standing rock spire appears as a sharp black obelisk below and to the right of the main summit of Pucaraju (16,486 feet). As I approached it after soloing the main summit on September 1, I expected the several hundred feet of vertical rock above an initial chimney to be well beyond my ability. I also expected to find rappel slings or other signs of prior ascents. To my pleasant surprise, the black rock turned out to be exceptionally firm, water-stained quartzite with sharp edges. On the way up I found no evidence of prior climbs, although the summit had plenty of loose rocks that could be easily arranged into a cairn. The crux proved to be down-climbing a 5.8 arête just below the top.