Hornfels thin section microscope slide exhibiting a dark colour and a characteristic none crystalline form. Fine grains fit together like the fragments of a mosaic, this is often referred to as rough pavement or pavement structure. Larger quartz clasts are visible but these have recrystallised to form a fine, interlocking mosaic of quartz within the original grain cast.

A thin section of mylonite which was collected from the metamorphic region of Lom, Central Norway. Mylonite is a fine-grained, compact rock produced by dynamic recrystallisation of the constituent minerals resulting in a reduction of the grain size of the rock.