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
Roadside exposure of mylonite in Roses, Catalonia. The mylonite here is located in an area of shear zones running across Variscan granodiorite in the southern part of the Cap de Creus peninsula.

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.

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