Basaltic hyaloclastite lava flow. Augite, olivine, and hornblende phenocrysts in a slightly vesicular groundmass of plagioclase microlites, olivine, augite, and dark brown devitrified glass. Olivine phenocrysts occur as both large euhedral and small akelatal [sic] crystals. Augite commonly occurs in rounded clots of augite +/- olivine. Plagioclase is absent as a phenocryst but several rounded, sieve textures crystals are present as xenocrysts.
Petrology, geochemistry, and the evolution of magmas from Augustine Volcano, Alaska