| Text Description: |
Silicic flow, 75 - 100’ thick, forming the ridge top on the west side of Goat Creek. Upper red, slightly vesicular zone that is underlain by an upper vitrophyre. Middle is platy, but otherwise similar to the vitrophyre. There is a basal vitrophyre. Sample is from the upper vitrophyre. Fine grained, hypocrystalline, flow banded, porphyritic with a matrix of devitrified brown glass, cryptocrystalline material, opaque and plagioclase. Plagioclase phenocrysts are up to 2.05 mm and occasionally display oscillatory zoning or resorbed edges. Clinopyroxene phenocrysts are up to 0.5 mm. Orthopyroxene phenocrysts are up to 0.85 and some have opaque inclusions. Opaque phenocrysts are up to 0.2 mm. 95.9% matrix, 2.9% plagioclase, 0.7% orthopyroxene, 0.3% clinopyroxene, 0.2% opaque. |