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SYENITE   (detail)

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Another specimen

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Typical Minerals
ORTHOCLASE - 65-100%
Plagioclase - 0-35%
Mafics - < 10%
Quartz - 0-5%
Detail Description
     In this detail the pinkish colored orthoclase stands out clearly. The white translucent mineral is sodium plagioclase. There is some quartz in this specimen, most obviously the clear, glassy, grayish grain just left of center, and a similar grain on the right side of the specimen. It may be enough to call this a "quartz syenite" although this close up was taken on just about the only part of the specimen with quartz on it. The rock as a whole probably has less than 5% quartz.
     The black (mafic) mineral is mostly amphibole, although there may be some biotite mixed in with it. Note that the mafic minerals make up only about 5% of the rock.
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