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Porphyritic Andesite
Field Collector: Esper Signius Larsen Jr.
Place Collected:Corona Quadrangle, Southern California
Object number: Cor 108
DescriptionDark grey-blue porphyritic volcanic rock consisting of 40% plagioclase phenocrysts (1-3 mm) and 10% hornblende phenocrysts (1-3 mm) that are revealed to be replaced by chlorite in thin section. The matrix is mostly glass and some plagioclase and quartz with minor amounts of epidote (< 0.5 mm) and magnetite (~0.5 mm).
In Collection(s)