Romanèchite ((Ba,H2O)2(Mn4+,Mn3+)5O10) is the primary constituent of
psilomelane, which is a mixture of
minerals. Most psilomelane is not pure romanechite, so it is incorrect to consider them synonyms. Romanèchite is a valuable
ore of
manganese, which is used in
steelmaking and sodium battery production.[6] It has a
monocliniccrystal structure, a
hardness of 6 and a
specific gravity of 4.7–5. Romanèchite's structure consists of 2 × 3 tunnels formed by MnO6 octahedra.[5][7]
Bicolor (left) and tricolor (right) X-ray fluorescence maps of the distribution of Mn, Fe, and Ba in a ferromanganese nodule from Lake Baikal. Size = 5 mm (H) × 3 mm (V).[9]
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abManceau A, Kersten M, Marcus MA, Geoffroy N. and Granina L (2007) "Ba and Ni speciation in a nodule of binary Mn oxide phase composition from Lake Baikal". Geochimica et Cosmochimica Acta, 71: 1967–1981.
doi:
10.1016/j.gca.2007.02.007