A large K-feldspar porphyroclast in a mylonite of syenitic composition (no quartz;
95MW0212) shows evidence of movement on a fine fracture. Note the growth of finer grains of plagioclase and microcrystalline muscovite in the “shadows” of the faulted porphyroclast. K-feldspar has been stained green, and Na-rich string perthite appears gray.
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