Phyllite is a fine-grained metamorphic rock formed from slate, displaying a silky sheen due to platy minerals. It is softer and more foliated than slate, with a glossy, wavy surface. In geology and mineralogy, phyllite lies between slate and schist in its degree of metamorphism and foliation, often hosting muscovite and chlorite. The term denotes a characteristic layered texture observable under light.
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