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Phyllite is a foliated metamorphic rock formed from slate which has been further metamorphosed. These specimens from Kinlochleven in Scotland and show good, fine cleavage and a silky metallic lustre.
Phyllite is a type of foliated metamorphic rock created from a slate or pelite protolith that has further metamorphosed so that very fine grained white mica achieves a preferred orientation. It is primarily composed of quartz, sericite mica, and chlorite. Sometimes minute crystals of graphite, sericite, or chlorite, or the translucent fine-grained white mica, impart a silky, sometimes golden sheen to the surfaces of cleavage, called "phyllitic luster". These examples are from Kinlochleven, Scotland. Specimens are supplied in a labelled card tray.