This texture allows the rock to be broken into thin slabs along the alignment direction of the platy mineral grains. Banding in it … From this photo it is easy to understand why clean, gem-quality garnets with no inclusions are very hard to find. In Australia, houses that were built using schist in the 1800s are still standing today. It has been previously used to make decorative rock walls. The initial sedimentation of particles forms sandstone and mudstone. It usually forms on a continental side of a convergent plate boundary where sedimentary rocks, such as shales and mudstones, have been subjected to compressive forces, heat, and chemical activity. There are many varieties of schist and they are named for the dominant mineral comprising the rock, e.g. to medium grained; can often see crystals with the naked eye. metamorphic rocks in which individual minerals can be seen with the naked eye. Schist is a foliated metamorphic rock made up of plate-shaped mineral grains that are large enough to see with an unaided eye. Most of the this rock contains the mineral mica and is called mica schist. The specimen shown is about two inches (five centimeters) across. Phyllite is composed mainly of tiny grains of mica minerals such as muscovite, or sericite. Geological foliation (metamorphic arrangement in layers) with medium to large grained flakes in a preferred sheetlike orientation is called schistosity. A rock does not need a specific mineral composition to be called “schist.” It only needs to contain enough platy metamorphic minerals in alignment to exhibit distinct foliation. them even when completely recrystallized. Schist has a flat, large and sheet-like grains and It have flat and elongated minerals such as talc or micas.It has quartz and feldspar minerals are intertwined.These lamellar (flat, planar) minerals include micas, chlorite, talc, hornblende, graphite, and others. Individual mineral grains are discernible by the naked eye. Its platy grains are aligned in a common orientation, and that allows the rock to be split easily in the direction of the grain orientation. The graphitic schists may represent sediments once containing coaly matter or plant remains. (2020). Other common minerals in schist include quartz and feldspars that are inherited from the protolith. If Chlorite schist: A schist with chlorite as the dominant visible mineral is known as a "chlorite schist." Mineral and/or Locality . others are determined only among igneous masses, and but advanced the The hardness of Schist is 3.5-4 and that of Phyllite is 1-2. Chemical - If the general chemical composition can be determined from the mineral assemblage, then a chemical name can be employed. This is because their mineral crystals grow within the rock matrix, often including mineral grains of the host rock instead of replacing them or pushing them aside. This texture allows the rock to be broken into thin slabs along the alignment direction of the platy mineral grains. Mica Schist is a very interesting rock. The garnet has grown by replacing, displacing, and including the mineral grains of the surrounding rock. Phyllite has fine-grained mica flakes in a preferred orientation, whereas slate has extremely fine clay flakes that achieve a preferred orientation, and schist has large flakes in a preferred orientation. Micas, feldspars, and quartz usually account for most of the minerals present in a schist. The specimen shown is about two inches (five centimeters) across. Banding in it is typically poorly developed. The best way to learn about rocks is to have specimens available for testing and examination. Chemical - If the general chemical composition can be determined from the mineral assemblage, then a chemical name can be employed.