Romanèchite

romanechite

psilomelane

braunite

pyrolusite

Images

Formula: (Ba,H2O)2(Mn4+,Mn3+)5O10
Multiple oxide, manganese-bearing mineral
Specific gravity: 4.71
Hardness: 5 to 6
Streak: Brownish black to black
Colour: Iron black to grey
Environments:

Sedimentary environments
Hydrothermal environments

Romanèchite is a weathering product of manganese-bearing oxides, carbonates, and silicates in sedimentary deposits (Webmin, HOM). It also occurs as replacement deposits in limestone and dolostone, and is a principal component of “psilomelane" formed on rocks in arid regions (HOM). It is associated with pyrolusite, hausmannite, chalcophanite, braunite, goethite, calcite and quartz (HOM).

Localities

At the Mount Kelly deposit, Gunpowder District, Queensland, Australia, the copper ores overlie primary zone mineralisation consisting of quartz-dolomite-sulphide veins hosted in siltstone and schist. Romanèchite occurs as globules to 2 mm with chrysocolla, lining fractures in siltstone (AJM 22.1.22).

In the Caldbeck Fells, Cumbria, England, UK, romanèchite is common in lead veins at many mines (JRS9.39-44).

At Burdell Gill, Coombe Height, Caldbeck, Allerdale, Cumbria, England, UK, romanèchite is associated with pyrolusite (JRS8(1).1-9).

At Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK, romanèchite is associated with pyromorphite (JRS11.3-28).

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