xisto stone

leaf green soil geology tree autumn nature flower yellow water boulder stonewall wildlife stream wood wall grass trunk xisto stone shist medium-grained metamorphic showing pronounced schistosity means composed mineral grains easily low-power hand oriented split flakes plates reflects high content platy minerals micas chlorite graphite interleaved granular feldspar quartz metamorphism accompanying process mountain orogeny usually medium grade metamorphism form different kinds rocks sedimentary mudstones tuffs metamorphosed mudstone particularly common mica original protolith discernible reflecting schistose metasandstone civil engineering because planes weakness