MnO2, or manganese dioxide, is a black or brown solid that occurs naturally as the mineral pyrolusite. It is primarily composed of manganese and oxygen, with the chemical formula MnO2. This compound is commonly used in batteries, particularly in alkaline batteries, where it acts as a cathode material. In addition to its use in batteries, MnO2 is also employed in various industrial processes, such as glass production and as a catalyst in chemical reactions. It plays a role in the production of chlorine and in the purification of drinking water by removing impurities.