Pyrolusite

 

One of the most common manganese ore minerals, pyrolusite is used in making steel. It is widespread in its occurrence, forming in lacustrine, shallow marine, and bog deposits. It was named in 1827 from the Greek word for “fire” and “to wash” because it was used to remove brown and green tints in the making of glass.

Mineral Photos courtesy of R.Weller/Cochise College