Specimen 47AC88 (130,550' E., 270,000' N.) is from one of the longer flows of Mount Cerberus that reached the coast. It is a medium-light-gray (N 6) porphyritic basaltic andesite; most of the visible phenocrysts are plagioclase, averaging An82, but there are also olivine, hypersthene, augite, and magnetite crystals. The olivine and augite are commoner and in larger crystals (0.5 mm in diameter), than the hypersthene. The groundmass consists of plagioclase microlites with augite and magnetite and a mesostasis of glass.
Geologic reconnaissance of Semisopochnoi Island, western Aleutian Islands, Alaska