Gneiss is a type of metamorphic rock characterized by its distinct banding and foliation. It forms from the alteration of granite or schist under high temperature and pressure conditions, which causes minerals to realign and create a layered appearance. Common minerals found in gneiss include quartz, feldspar, and mica. Gneiss is often used in construction and landscaping due to its durability and aesthetic appeal. Its unique patterns and colors make it a popular choice for countertops, tiles, and decorative stonework. The rock can be found in various locations around the world, often in mountainous regions.