Phyllite is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation. It is primarily composed of quartz, sericite mica, and chlorite.The minute crystals of graphite, sericite, or chlorite, or the translucent fine-grained white mica, impart a silky, sometimes golden[citation needed] sheen to the surfaces of cleavage, called “phyllitic luster”.

Phyllite is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation. It is primarily composed of quartz, sericite mica, and chlorite.The minute crystals of graphite, sericite, or chlorite, or the translucent fine-grained white mica, impart a silky, sometimes golden[citation needed] sheen to the surfaces of cleavage, called “phyllitic luster”.