Todorokite (Mn,Ca,Mg)Mn3O7.H2O 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).