Specimen 47AC99 is olivine basalt from one of the latest flows from Ragged Top (148,800' E., 276,000' N.). The flow is about 20 feet thick, consists of medium-gray (N5) holocrystalline-porphyrytic dosemic basalt, with pilotaxitic texture. The phenocrysts consist of plagioclase (2 mm in diameter), averaging about An82, olivine (0.5 mm in diameter), augite (2 mm in diameter) that is dark green in hand specimen, and magnetite (0.5 mm in diameter). The groundmass consists of magnetite, augite, plagioclase, and interstitial orthoclase (?) .
Geologic reconnaissance of Semisopochnoi Island, western Aleutian Islands, Alaska