Polyhedral representation of the 2 x 3 tunnel structure of romanèchite. The red atoms represent Ba and H2O.[5]
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]
^ 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