Formula: (Ca,K,Na,Mg,Ba,Mn)(Mn,Mg,Al)6O12.3H2O Monoclinic
Description: Todorokite is soft sooty brown, gray to black mineral formed as a result of the alteration of other manganese minerals or as a precipitate from surficial waters.
Todorokite is reported as a component of the small manganese nodules found at various sites in Lake Michigan, particularly in Green Bay. (Rossman, et. al., 1972).