Pyrolusite is a mineral composed primarily of manganese dioxide (MnO2). It is typically found in black or dark gray colors and has a metallic luster. This mineral is an important ore of manganese, which is used in steel production and various chemical processes. In nature, pyrolusite often forms through the weathering of manganese-rich rocks. It can be found in sedimentary deposits and is commonly associated with other minerals like manganite and hausmannite. Due to its high manganese content, pyrolusite plays a crucial role in the manufacturing of batteries and fertilizers.