Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite.

Psilomelane has no definite chemical composition and occurs as botryoidal and stalactitic masses with a smooth shining surface and submetallic lustre.

The mineral is readily distinguished from other hydrous manganese oxides (manganite and wad) by its greater hardness 5 to 6; the specific gravity varies from 3.7 to 4.7.

The name, dating back to 1758, makes reference to its characteristic appearance, from the ancient Greek ψιλός: psilos for (naked, smooth, bald) and μέλας: melas (black); a Latinized form is calvonigrite from calvo for (bald, smooth) and negri (black).

It is found at many localities; amongst those which have yielded typical botryoidal specimens may be mentioned the Restormel iron mine at Lostwithiel in Cornwall, Brendon Hills in Somerset, Hoy in Orkney, Sayn near Coblenz, Hout Bay near Cape Town, and Crimora in Augusta county, Virginia.