Coronadite

minerals

pyrolusite

cryptomelane

hollandite

Images
Formula: Pb(Mn4+6Mn3+2)O16
Multiple oxide, cryptomelane group
Specific gravity: 5.44
Hardness: 4½ to 5
Streak: Brownish black
Colour: Dark grey to black
Common impurities: Fe,Al,H2O
Environments:

Sedimentary environments
Metamorphic environments
Hydrothermal environments
Hot springs

Coronadite occurs as a primary mineral in hydrothermal veins or hot springs, and it is of secondary origin in oxidised zones above manganese deposits and bedded sedimentary rocks. hollandite, pyrolusite and other manganese oxides are common associates (HOM).

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