Manganosite is a rare mineral composed of manganese(II) oxide MnO.

[4] It has also been reported from Langban and Nordmark, Sweden and at Franklin Furnace, New Jersey.

It also occurs in Japan, Kyrgyzstan and Burkina Faso.

It also occurs as alteration of manganese minerals such as rhodocrosite during low oxygen metamorphism and metasomatism.

[5] This article about a specific oxide mineral is a stub.