Mylonite

An amphibolitic mylonite showing a number of (rotated) porphyroclasts: a clear red garnet left in the picture while smaller white feldspar porphyroclasts can be found all over. Location: the tectonic contact between the (autochthonous) Western Gneiss Region and rocks of the (allochthonous) Blåhø nappe on Otrøy, Caledonides, Central Norway.
A mylonite (through a petrographic microscope) showing rotated so-called δ-clasts. The clasts show that the shear was dextral in this particular cut. Strona-Cenery zone, Southern Alps, Italy.
Mylonite, Owl Mountains, Poland

Mylonite is a fine-grained, compact metamorphic rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock. Mylonites can have many different mineralogical compositions; it is a classification based on the textural appearance of the rock.