A compact, chertlike rock without cleavage, but with a banded appearance produced by extreme shearing and pulverizing during metamorphism.
fine-grained rock, with a more or less ribbony texture, deriving from intense crushing of country rocks inside deep-sited faults or overthrusts.
Mylonite is a fine-grained, compact rock without cleavage or crystals. It is classified as a metamorphic rock and has a flow texture. Mylonites can have many different mineralogical compositions, it is a classification on the appearance of the rock.