Manganite

minerals

acanthite

cinnabar

pyrolusite

Images
Formula: Mn3+O(OH)
Oxide containing hydroxyl
Specific gravity: 4.3 to 4.4
Hardness: 4
Streak:
Colour: Brownish black to black
Solubility: Slightly soluble in hydrochloric acid; moderately soluble in sulphuric acid
Environments:

Pegmatites
Hydrothermal environments

Manganite is found associated with other manganese oxides in deposits formed by meteoric waters. It is often found in epithermal (low temperature) hydrothermal veins associated with acanthite, baryte, cinnabar, pyrolusite, quartz, siderite and calcite.
It frequently alters to pyrolusite.

Localities

At and near Ilfeld, Harz mountains, Germany, manganite pseudomorphs after calcite, and also hausmannite pseudomorphs after manganite, have been found (KL p146).

At Hartshill, Nuneaton, Warwickshire, England, UK, manganite occurs with manganoan calcite (RES p321).

At the South Hecla mine, Calumet, Houghton county, Michigan, USA, tiny crystals of manganite have been found associated with quartz, epidote and albite in voids in the conglomerate which hosts the mineralisation (R&M 94.6.564).

At the Tamarack Jr. No. 1 mine, Calumet, Houghton county, Michigan, USA, tiny crystals of manganite have been found in vugs of crystallised albite (R&M 94.6.564)

At the Central No. 2 mine, Keweenaw county, Michigan, USA, tiny crystals of manganite have been found in vugs in crystallised albite associated with epidote and actinolite, and sometimes also with hematite or copper (R&M 94.6.564).

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