锶 (sī) is a chemical element with the symbol Sr and atomic number 38. It is a soft, silvery-white metal that belongs to the alkaline earth metals group. Found in nature primarily in the mineral celestine,锶 is known for its bright flame when burned, which produces a characteristic crimson color. In addition to its aesthetic properties,锶 has various applications. It is used in fireworks to create red colors and in the production of strontium carbonate, which is utilized in ceramics and glass. Additionally,锶 isotopes are studied for their potential use in medical imaging and treatments.