A mineral consisting of hydrated basic oxide of manganese and barium

• A source of manganese

Wiktionary Word definitions in Wiktionary
n. Any hard, black hydrous manganese oxide with variable amounts of barium and potassium.

WordNet Word definitions in WordNet
n. a mineral consisting of hydrated basic oxide of manganese and barium; a source of manganese

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Psilomelane \Psi*lom"e*lane\, n. [Gr. ? bare + ?, ?, black.] (Min.) A hydrous oxide of manganese, occurring in smooth, botryoidal forms, and massive, and having an iron-black or steel-gray color.

Wikipedia Word definitions in Wikipedia
Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite . Psilomelane consists of hydrous manganese oxide with variable amounts of barium and potassium . Psilomelane is erroneously, and uncommonly, known as black ...