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Formula: (Ba,H2O)2(Mn4+,Mn3+)5O10
Multiple oxide, barium- and
manganese- bearing mineral
Crystal System: Monoclinic
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 Dry Gill Mine, Caldbeck, Allerdale, Cumbria, England, UK, romanèchite occurs as sooty black deposits or
botryoidal aggregates, associated with mimetite variety campylite
(AESS).
Romanèchite from the Dry Gill Mine - Image
At Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK, romanèchite is associated with
pyromorphite
(JRS11.3-28).
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