Pyrolusite
Species
Common · MnO₂
A main ore of manganese; the soft, powdery masses are sooty enough to blacken the fingers. The branching black dendrites on rock joints, often mistaken for fossil plants, have long been called pyrolusite, but analysis shows they are mostly other manganese oxides.
Identity
- Formula
- MnO₂
- Chemical class
- Oxide
- Mineral group
- Cassiterite, Rutile
- Also known as
- Grey manganese ore
- Ore of
- Manganese
Crystallography
- Crystal system
- Tetragonal
- Habits
- Dendritic, Botryoidal, Massive, Earthy
- Fracture
- Uneven
Physical properties
- Mohs hardness
- 6
- Density
- 5.06 g/cm³
- Luster
- Metallic, Earthy
- Colors
- steel gray, iron gray, bluish gray
- Streak
- black
- Transparency
- Opaque
Geology
- Origins
- Sedimentary, Hydrothermal
- Host rocks
- Limestone and chalk
- Associated minerals
- Manganite, hollandite, Goethite, Hematite
- Found in
- Oxidized zone (gossan)
- Geography
- Germany, Czech Republic, USA, Canada
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- Pyrolusite. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Pyrolusite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- R. M. Potter, G. R. Rossman, The mineralogy of manganese dendrites and coatings. American Mineralogist 64, 1219-1226, 1979.
Browse the Crystal Encyclopedia — MGS Toolbox