Manganite

oxide

pyrolusite

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.

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

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