Gneiss is a metamorphic rock that is widely distributed. Its mineral content is mainly feldspar, quartz and mica. These minerals are ingrained in gneiss in such a way that they are still visible to the naked eye. This rock is normally gray or pink with dark streaks and layers that give it a distinctive look. The bands are alternatively light and dark. The light layers are because of the presence of quartz and feldspar. The dark layers are because of the presence of mica. Even though there are bands in gneiss it resist being split or breaking where it has its color bands. This is due to the process that this rock underwent which occurred deep beneath the Earth’s surface. The pressures occurring causes the fusing of minerals and existing rock thus creating metamorphic rock. You might say the rock and minerals become one mass under pressure a so called “metamorphosis”. The correct term used for this process of change that is undergone is metamorphism.
Gneiss is similar to granite but much harder. Just as granite is used in construction for floors and counter tops and other applications gneiss can also be used. The more popular use though is for stone facing in buildings. They are also used as ornamental stone and as tombstones and gravestones. Because of its durability gneiss is popular for work surfaces that have to endure heavy traffic. It is shaped into tiles, counter top and sink components. In its application as an ornamental stone generally one side is polished to reveal the colorful characteristics of this material and the other side is left unpolished for contrast. It is also used for building roads and roadside curbs. When people buy granite especially for counter tops there is a good chance they are buying gneiss. Once polished this stone has great eye appeal and on certain occasions generally they are treated as semi-precious stones commonly in spherical form.
It is formed as rock and minerals combine under high temperature and pressure. Rocks melt and fuse together. Sometimes igneous but more often metamorphic rock combines with certain minerals combine to create gneiss. The mineral content is what causes the color and the varying shades of gneiss.
This rock is obtained by underground mining. Normally they are sourced from mountainous regions. This makes sense because mountains provide the elements of earth depth, and as they are being created, the elements of heat and pressure that turns magma into igneous and metamorphic rock.