Transformations of ore minerals in genetically different oceanic ferromanganese rocks

Results of thermic transformations of ore minerals from genetically different oceanic ferromanganese rocks in the course of their heating up to 1000°C are considered. Manganese minerals with various types of crystalline lattice have different grades of thermic stability. Layered manganese minerals (buserite I, asbolane-buserite, and birnessite) are stable up to 120–150°C; asbolane up to 180°C, vernadite, up to ～500°C; todorokite and pyrolusite (minerals of the tunnel group), up to 600 and 670°C, respectively. Sorbed cations of heavy metals govern the transformation temperature and mineral composition of products of the calcination of ferromanganese rocks. Study of birnessite and todorokite demonstrated that genesis of ferromanganese rocks do not affect thermic properties of minerals in them.