Slate, phyllite, schist, gneiss, what is the petrological characteristics
black hard chlorite or manganese aluminum garnet and other variable crystal
Sometimes, the mineral composition is serpentine, chlorite and quartz. There are a small amount of calcite, crystal pebbles
A typical mineral assemblage of sericite, chlorite and quartz, with a small amount of feldspar and carbonaceous, iron and other substances
Often fine grain scale crystal structure, particle size is less than 0.1 mm, in the film surface often small wrinkle structure
