Pyrolusite

Real mineral · common · MnO₂

The main ore of manganese, sooty enough to blacken the fingers. Its dendritic films spread along rock joints in branching black patterns often mistaken for fossil plants.

Identity

Formula

MnO₂

Chemical class

oxide

Mineral group

Cassiterite, Rutile

Also known as

Grey manganese ore

Crystallography

Crystal system

tetragonal

Habits

dendritic, botryoidal, massive, earthy

Fracture

uneven

Physical properties

Mohs hardness

6

Density

4.73 g/cm³

Luster

submetallic

Colors

steel gray, iron gray, bluish gray

Streak

black

Transparency

opaque

Geology

Origins

sedimentary, hydrothermal

Host rocks

manganese ore, limestone

Associated minerals

Goethite, Hematite, Quartz, Barite

Geography

Germany, India, Brazil

Classification

Rarity

common

Gem quality

No

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