In mixtures in "psilomelane" with other manganese oxides in an iron oxide deposit, probably bacterially altered from a previous mineral (Akhtensk deposit, Russia); in incrustations of ferromanganese minerals on oceanic
Approved IMA 1979
In the Akhtensk brown ironstone deposit, Southern Ural Mountains, on Mt. Zarod, Sikhote-Alin Mountains, Primorskiy Kray, Russia. Link to MinDat.org Location Data.
For the Akhtensk deposit, Russia, where it was first noted.