Explain what is ferromanganese nodules in geology

Ferromanganese nodules and scabs are hydrogenetic deposits (precipitation  mineral from seawater) and diagenetic (mineral precipitation  from intrasedimentary fluids in the compaction and lithification processes of  sediments).

Explanation:

The nodules show concentric shapes from a precipitation core and the scabs are bands that are arranged on various seafloor surfaces. Both consist mainly of oxides and hydroxides of manganese (Todorokita and Vernardite: δ MnO2) and iron (Feroxyhyta: δFeOOH. X H2O), although they contain significant and variable amounts of other metals such as copper, nickel, cobalt, etc. Both the nodules and the scabs represent important resources of metals such as Mn, Fe, Ni, Cu, Co, Mo and, to a lesser extent, Zn, Ti, Pb, Pt, As. The scabs usually have more Co and less Fe and Mn than the nodules.

In general, the origin of the metallic components of these materials comes from the magmatic activity of the ocean, from the contributions of chemical elements from continental waters and winds and from chemical components contained in marine organisms, which are released upon death and decomposition. . Thus, more than ten million m3 of oxides and hydroxides of Mn, Fe, Ni, Cu, Co, which are dissolved in seawater, precipitate every year on the manganese nodules and crusts of the ocean floor.