Gneiss is a medium to course grained metamorphic rock.
Shale is the typical parent rock. It is made up of clay minerals. Shale can metamorphose into slate, phyllite, schist or gneiss depending on the degree of heat and pressure. Gneiss has the greatest degree of metamorphism in this group. It is classed as a high-grade metamorphic rock and is associated with regional metamorphism do to major mountain building.
Igneous rocks especially granite, can also make up the parent rock for gneiss.
This is a foliated dense rock that has light and dark colored banding. It is typically composed of feldspars, quartz, micas, and amphiboles. Because of the high heat and pressure, the minerals contained in gneiss have been mostly recrystalized.
Gneiss is a very common metamorphic rock.Back to Examples of Metamorphic Rocks