长石, or feldspar, is a group of rock-forming minerals that make up about 60% of the Earth's crust. It is primarily composed of aluminum silicates combined with potassium, sodium, or calcium. Feldspar is commonly found in igneous, metamorphic, and sedimentary rocks, playing a crucial role in the formation of granite and other types of rocks. There are two main types of feldspar: 长石 and 钠长石. These minerals are important in various industries, including ceramics, glass manufacturing, and as fillers in paints and plastics. Their unique properties, such as hardness and resistance to weathering, make them valuable in both natural and industrial applications.