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Manganosite
7 in the gallery
Manganosite is a simple manganese oxide mineral. It typically forms in oxidized environments and can present a metallic to dull lustre with a brownish to black appearance. Crystals, when seen, are commonly small and compact, while masses can appear earthy or granular. The mineral’s color and surface sheen reflect its MnO composition and oxidation state, yielding a material that collectors notice for its understated, mineralogical character.
- Formula
- MnO
- Rarity
- Rare
- Stability
- Unstable
- Collector interest
- Moderate Interest
- Classification notes
- Oxide; simple oxide, periclase group
Key characteristics
- Crystal system
- isometric
- Mohs hardness
- 5.5–6
- Specific gravity
- 5.18–5.43
- Luster
- vitreous, dull
- Transparency
- translucent, opaque
- Color
- green, black, brown
- Streak
- brown, green
- Cleavage
- perfect
- Fracture
- uneven
- Crystal habit
- cubic, octahedral, granular, massive
Where Manganosite is found
Top localities
- Franklin Mine2 specimens
About Manganosite
Notable specimens have been found in the United States and Sweden, where secondary manganese oxide assemblages occur in oxidized deposits. Localities contribute to the mineral’s presence in collections that emphasize alteration products and manganese-rich environments. Collectors often value manganosite for its straightforward chemistry, its role as a manganese-oxide reference, and the way it complements specimens of more complex Mn-bearing minerals. While not highly flashy, its consistency and locality connections make it a useful addition for those building a comprehensive oxide suite.
