Gneiss is a high grade foliated metamorphic rock. Gneiss is formed with high temperature (650-800 C) and high pressure (3-7Kbar). Gneiss may have a protolith of any kind of rock, be it igneous, sedimentary, or another metamorphic rock. Gneiss is often confused with or associated with granite. This is because Migmatite gneisses contain melted rock and can act as feeder zones for granite minerals.