Groutite
Mineral MnO(OH)
About it
Black, wedge-shaped, lustrous crystals of manganese hydroxide, the orthorhombic partner of manganite. First found in the Cuyuna iron range of Minnesota; named for American geologist Frank Grout.
- Type
- Mineral
- Group
- Hydroxide, diaspore group
- Formula
- MnO(OH)
- Hardness (Mohs)
- 5.5
- Specific gravity
- 4.1–4.2
- Streak
- dark brown
- Lustre
- adamantine (diamond-like), submetallic
- Crystal system
- Orthorhombic
- Colours
- black, blue-black
- Transparency
- opaque
- Cleavage and fracture
- perfect in one direction
Typical values: real specimens vary. For more, see mindat.org.