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Santiago Peak Volcanic Intrusive
Field Collector: Esper Signius Larsen Jr.
Place Collected:Near San Marcos San Luis Rey Quadrangle, Southern California
Object number: ROC21739
DescriptionDark grey fine grained (1 mm) plutonic rock with tan plagioclase phenocrysts (~2 mm) and black hornblende phenocrysts (up to 3 mm). The groundmass is revealed to be mostly quartz in thin section.
In Collection(s)