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| PLAGIOGRANITE (detail)
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Typical Minerals QUARTZ > 20% PLAGIOCLASE is greater than Orthoclase (here virtually none) Mafics - < 10% (here < 5%) MUSCOVITE - trace (brassy looking) |
Detail Description
In this detail the plagioclase stands out clearly. The quartz is harder to see in the photo, but are clear grains, grayish not white, scattered among the plagioclase crystals. Mafics are few but consist of biotite crystals. There is also muscovite (or this muscovite in an alkali granite) in this specimen but it just does not show up in the photograph; you must rotate the crystal in the light under a microscope for it to show up. |
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| Last Update: 9/29/00 | e-mail: (Fichtels@jmu.edu) |