Ugashik A-3. southeast side of Mount Kialagvik. Medium- to fine-grained, medium-gray (N5), hyalopilitic andesite (S; high-silica andesite G) porphyry containing very light gray (N 8) plagioclase phenocrysts and sparse dark-greenish-gray (5 G/Y 4/1) pyroxene phenocrysts. Major minerals are plagioclase (An 64), clinopyroxene, and lesser opaque oxides. Abundant phenocrysts in groundmass of glass and very fine grained plagioclase. Most phenocrysts and crystals have resorbed edges.
Map and tables showing geochronology and whole-rock geochemistry of selected samples, Ugashik and part of Karluk quadrangles, Alaska