Black hypersthene augite andesite. Sample of andesite flow from the rim of the active crater located on the south margin of the caldera. The flow is composed of plagioclase phenocryst, microphenocrysts of plagioclase, augite and hypersthene, surrounded by a matrix of glass. The glassy mesostasis also includes disseminated magnetite grains and microlites of pyroxene.
The reconnaissance petrology of andesites from the Mount Wrangell Caldera, Alaska