Manganese dioxide, the most common manganese mineral, typically black and often forming dendritic patterns or sooty masses (can soil hands). It's a stone of transformation, optimism, and repelling negativity.
Iron-Black, Steel-Grey, Bluish-Grey, often forms dendritic (fern-like) patterns or massive, sooty (can soil fingers)
Pyrolusite is classified as a oxide minerals mineral which typically crystallizes in the tetragonal system. Its chemical formula is MnO2. Common crystal habits include granular to massive: botryoidal. crystals rare.