Romanechite From Spain- Collectors PieceRomanechite From Spain Collectors Piece (Stand Included) Weight 120g Size 6. 5cm by 5cm Thickness 4cm Romanechite, barium and manganese oxide [(Ba, H2O)2(Mn4+, Mn3+)5O10], an important ore mineral of manganese. A secondary mineral formed under surface conditions, it is often a dark gray to black alteration product of manganous carbonate or silicate minerals. It may form large residual deposits and occurs abundantly in lake or swamp bedded deposits and