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

Sedimentary environments

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

In the Caldbeck Fells, Cumbria, UK, romanèchite is common in lead veins at many mines. At Burdell Gill it is associated with pyrolusite, and at Roughton Gill it is associated with pyromorphite.

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