Phyllite
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PhylliteUSGOV.jpg
PhylliteUSGOV.jpg
Phyllite is a type of metamorphic rock primarily composed of quartz, sericite mica, and chlorite; the rock is intermediate in grade between slate and mica schist. Minute crystals of graphite, sericite, or chlorite impart a silky sheen to the surfaces of cleavage (or schistosity).