6 Photos
Manganosite
Chemical Formula	Manganese oxide, MnO
Species	Oxides & Hydroxides
Crystal System	Isometric
Mohs Scale	5
Specific Gravity	5.18
Color	Emerald-green, becoming black on exposure to air
Streak	Brown
Luster	Vitreous
Diaphaneity	Transparent, Translucent
Cleavage	Perfect on , and
Fracture	Fibrous
Crystal Habit：Granular to massive: Crystals rare

Manganosite is a rare mineral composed of manganese(II) oxide MnO. It was first described in 1817 for an occurrence in the Harz Mountains, Saxony-Anhalt, Germany. 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 occurs in manganese nodules. It also occurs as alteration of manganese minerals such as rhodocrosite during low oxygen metamorphism and metasomatism