Pyrolusite

Pyrolusite is the mineral representation of manganese dioxide and is an important ore of the element manganese. It has a silvery metallic luster, a black or bluish-black streak, and a soft texture. This mineral is commonly found in finely packed fibrous, acicular, and radial forms composed of very thin needles or fibers. Pyrolusite is believed to be manganite replaced by pyrolusite. Intermediary stages between the two minerals have been observed, suggesting that pyrolusite probably often pseudomorphs from manganite. Therefore, a more accurate name for these specimens would be pyrolusite-replaced manganites.