Pyrolusite is one of about two or three dozen blackish-colored manganese oxide or hydroxy-oxide minerals.  Distinguishing pyrolusite (MnO2 - manganese dioxide) from other Mn-oxides requires careful chemical analysis.  Pyrolusite, and Mn-oxides in general, have a reflective black color.  Pyrolusite (see sample below) has a metallic luster, a black streak, a hardness from about 1 to over 6, and often forms radiating acicular crystal clusters.


Pyrolusite is the most important manganese ore mineral.  Among other things, the Mn from pyrolusite is used in the steel-making process.


Pyrolusite (4.6 cm across)



Photo gallery of pyrolusite



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