Mineralpedia Details for Pyrolusite

Named after the Greek pyr, for “fire,” and louo, meaning “to wash,” in reference to Pyrolusite’s use due to its ability to pull tints from glass. Pyrolusite is a common mineral with many localities and can be found in highly oxidized manganese-rich hydrothermal deposits and rocks, in bogs, lakes, and shallow marine conditions, and can often be found as a product of altered manganite. It should be noted that dendritic Pyrolusite has never been found to be valid and ends up being other manganese oxide minerals.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/pyrolusite.pdf

Formula

MnO₂ 

Crystal System

Tetragonal 

Crystal Habit

Reniform, Dendritic, Earthy 

Cleavage

Perfect, None, None 

Luster

Sub Metallic 

Color

steel gray, iron gray, bluish gray 

Streak

black 

Class

Tetragonal - Ditetragonal Dipyramidal 

Fracture

Brittle 

Hardness

6-6.5 

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2cm fan aggregate crystal.

 The crystals are long 3-7mm blades. Paul Moore, the original owner, labeled it as "polianite", a variety of Pyrolusite. It was obtained by Paul from the Champion mine.