It has been established (with use of analytical electron microscopy) that Fe-Mn crusts from two seamounts of the Sea of Japan consist predominantly of an association of birnessite minerals including Ca-birnessite and clinobirnessite. The latter is represented by twins, which form regular integrowths with 14 Å Ca-birnessite. Ore material from the third seamount (Tarasov submarine volcano) consists only of fibrous todorokite, which forms spherulitic nodules, blocks, and laminar formations. Its chemical composition is close to that of todorokite from the Galapagos rift zone.

Supplement to: Gorshkov, Anatoly I; Berezovskaya, V V; Baturin, Gleb N; Sivtsov, Alexander V (1992): The nature of the iron-manganese crusts from seamounts in the Sea of Japan. Oceanology, 32(3), 364-369