Gneiss is a metamorphic rock often formed from high grade regional metamorphism, usually from pre-existing rock (known as the country rock). As the metamorphic processes are high grade, the original rock could have either been sedimentary or igneous. One of the most identifiable features of gneiss are its alternating dark and light foliations, known as banding, which are known as gneissic banding and composed of various dark and light coloured minerals. The dark bands are often comprised of mafic minerals such as pyroxenes where as the lighter coloured bands are felsic in chemical composition, often comprised of potassium, aluminium or silicate minerals. these specimens of gneiss differ in colour from our stock from Scotland (Lewisian gneiss) due to the fact that they contain more feldspar and quartz minerals and less of the dark mafic minerals such as pyroxene and thus are sometimes known as migmatitic gneisses. This gives them an overall pink colouration, but excellent banding detail can still be seen, making them perfect for use in sets, collections or for teaching and study use. This gneiss was collected by staff and comes from Evje, Norway, is available in 3 sizes and will come supplied in a card tray with an information label.