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DIORITE   (detail)

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Typical Minerals
PLAGIOCLASE & MAFICS (amphibole) about 50/50
Quartz - absent to trace
Detail Description
     In this detail we see the mixed amphibole and translucent, white sodium plagioclase. Some quartz is present (clear, glassy, grayish - as near the top center of the photo) but it is only about 5%. Note that the plagioclase and amphibole are near 50/50, with plagioclase being more abundant. It is this near mix that puts the rock in the diorite range.
     Orthoclase is absent.
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