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.[5] It has a monoclinic crystal structure, a hardness of 6 and a specific gravity of 4.7-5. Romanèchite's structure consists of 2 × 3 tunnels formed by Mn oxide octahedra.[6]

Romanèchite, from the Marquette County, Michigan, US.
CategoryOxide minerals
(repeating unit)
IMA symbolRmn[1]
Strunz classification4.DK.10
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Mohs scale hardness6-6.5

It is associated with hematite, barite, pyrolusite, quartz and other manganese oxide minerals. It has been found in France, Germany, England, Brazil, India, and various parts of the United States, including Arizona, Virginia, Tennessee and Michigan, and sites throughout the Appalachian Valley and Ridge.[7]


  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85: 291–320.
  2. ^ Romanechite,
  3. ^ Romanechite,
  4. ^ Harlow G, Peters J, Prinz M (1977). "Oxides and Htdroxides.". Simon & Schuster's Guide to Rocks and Minerals. New York: Simon & Schuster.
  5. ^ Li JY, Wu XL, Zhang XH, Lü HY, Wang G, Guo JZ, et al. (October 2015). "Romanechite-structured Na(0.31)MnO(1.9) nanofibers as high-performance cathode material for a sodium-ion battery". Chemical Communications. 51 (80): 14848–51. doi:10.1039/C5CC05739F. PMID 26344149.
  6. ^ Post JE (March 1999). "Manganese oxide minerals: crystal structures and economic and environmental significance". Proceedings of the National Academy of Sciences of the United States of America. 96 (7): 3447–54. Bibcode:1999PNAS...96.3447P. doi:10.1073/pnas.96.7.3447. PMC 34287. PMID 10097056.
  7. ^ Carmichael SK, Doctor DH, Wilson CG, Feierstein J, McAleer RJ (2017-09-01). "New insight into the origin of manganese oxide ore deposits in the Appalachian Valley and Ridge of northeastern Tennessee and northern Virginia, USA". GSA Bulletin. 129 (9–10): 1158–1180. doi:10.1130/B31682.1. ISSN 0016-7606.