| Manganosite | |
| Category: | Oxide mineral |
| Formula: | Manganese oxide, MnO |
| Imasymbol: | Mng[1] |
| Strunz: | 4.AB.25 |
| System: | Cubic |
| Class: | Hexoctahedral (mm) H-M symbol: (4/m 2/m) |
| Symmetry: | Fmm |
| Unit Cell: | a = 4.44 Å; Z = 4 |
| Color: | Emerald-green, becoming black on exposure to air |
| Habit: | Granular to massive; Octahedral crystals uncommon |
| Cleavage: | Perfect on [100], [010] and [001] |
| Fracture: | Fibrous |
| Mohs: | 5–6 |
| Luster: | Vitreous, adamantine to dull |
| Refractive: | n = 2.16–2.17 |
| Opticalprop: | Isotropic |
| Streak: | Brown |
| Gravity: | 5.364 |
| Diaphaneity: | Transparent to translucent |
| 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]