Feldspar is a group of rock-forming minerals that make up about 60% of the Earth's crust. They are primarily composed of aluminum, silicon, and oxygen, and are classified into three main types: orthoclase, plagioclase, and microcline. Feldspar minerals are essential in the formation of igneous rocks and are commonly found in granite and basalt. These minerals are not only important for geology but also have various industrial applications. They are used in the manufacture of glass, ceramics, and as fillers in paints and plastics. Their abundance and versatility make feldspar a significant component in both natural and human-made materials.