Todorokite
Mineral (Na,Ca,K)2Mn6O12·3-4.5H2O
About it
Soft, dark brown to black, fibrous or spongy manganese oxide, a main part of the manganese nodules on the deep sea floor. Named for the Todoroki mine in Hokkaido, Japan.
- Type
- Mineral
- Group
- Oxide, manganese oxide
- Formula
- (Na,Ca,K)2Mn6O12·3-4.5H2O
- Hardness (Mohs)
- 1.5
- Specific gravity
- 3.49–3.82
- Streak
- dark brown
- Lustre
- dull, submetallic
- Crystal system
- Monoclinic
- Colours
- dark brown, brownish black, black
- Transparency
- opaque
- Cleavage and fracture
- perfect in two directions
Typical values: real specimens vary. For more, see mindat.org.