ROMANECHITE (PSILOMELANE) (miniature)

Romanèchite ((Ba,H2O)2(Mn4+,Mn3+)5O10) serves as the main component of psilomelane, which is a composite of various minerals. However, most psilomelane does not consist solely of romanechite, making it inaccurate to equate the two. This mineral is an important source of manganese, utilized in steel production and the manufacturing of sodium batteries. Romanèchite features a monoclinic crystal structure, exhibits a hardness of 6, and has a specific gravity ranging from 4.7 to 5. Its unique structure includes 2 × 3 tunnels formed by MnO6 octahedra. 

In terms of associations, it is frequently found alongside hematite, barite, pyrolusite, quartz, and other manganese oxide minerals. Notable occurrences of romanechite have been documented in countries such as France, Germany, England, Brazil, Russia, and India, as well as in various regions of the United States, including Arizona, Virginia, Tennessee, and Michigan, particularly throughout the Appalachian Valley and Ridge. Additionally, it can be found in ferromanganese nodules from Lake Baikal.

Former John Betts Collection New York #11648