Gneiss rocks refer to a kind of high grade metamorphic rock. It has a banding of alternating layers which are composed of different minerals. These minerals can be granite, Feldspar, mica and quartz. Along with these minerals it can also be formed from sandstone or shale. The idea behind this rock is that the mineral grains get flattened in a Genesis rock by continuous heat and pressure that comes from the natural resources and gives the minerals an alternating pattern.
Gneiss is made from many different rocks and it is formed by a sedimentary rock that is compressed and heated intensely causing it to turn in to a metamorphic rock named gneiss (pronounced "nice") tnx 4 asking xxxxxxxx
Its made up of quartz and feldspar not mica. It used to be granite before it metamorphosed into gneiss.