Manganosite

Manganosite
Black manganosite crystals with zincite and sonolite
General
Category	Oxide mineral
Formula (repeating unit)	Manganese oxide, MnO
IMA symbol	Mng[1]
Strunz classification	4.AB.25
Crystal system	Cubic
Crystal class	Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m)
Space group	Fm3m
Unit cell	a = 4.44 Å; Z = 4
Identification
Color	Emerald-green, becoming black on exposure to air
Crystal habit	Granular to massive; Octahedral crystals uncommon
Cleavage	Perfect on [100], [010] and [001]
Fracture	Fibrous
Mohs scale hardness	5–6
Luster	Vitreous, adamantine to dull
Streak	Brown
Diaphaneity	Transparent to translucent
Specific gravity	5.364
Optical properties	Isotropic
Refractive index	n = 2.16–2.17
References	[2][3][4][5]

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.^[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.^[5]

It occurs in manganese nodules. It also occurs as alteration of manganese minerals such as rhodocrosite during low oxygen metamorphism and metasomatism.^[5]