Pyrolusite
Image: <a href="//commons.wikimedia.org/wiki/User:Islam90" title="User:Islam90">Islam90</a> (CC BY-SA 4.0)
Mineral NamePyrolusite
Chemical FormulaMnO2
Mohs Hardness6
Crystal Systemtetragonal
Lustermetallic
Streak Colorblack to bluish-black
Cleavageperfect on {110}
Fractureuneven
Specific Gravity4.75
Colorsblack, dark gray, steel gray
Transparencyopaque
Type LocalityElgersburg, Thuringia, Germany (type locality)
Mineral GroupOxides
Usesmanganese ore, dry-cell batteries, glass decolorizer, pigment
Associated Mineralsmanganite, psilomelane, goethite, hematite, quartz, calcite
Raritycommon
Description
This microscopic image shows Pyrolusite as an aggregate of dark, elongated, and irregular crystalline grains, appearing black against a lighter, reflective background in normal light.
Geological Context
Pyrolusite typically forms in oxidizing environments, often as a secondary mineral in sedimentary deposits, bog iron ores, and hydrothermal veins, or as an alteration product of other manganese minerals.
