psilomelane
/saɪˈlɑməleɪn/
noun
- A black or dark gray mineral that is a source of manganese, often found in rounded masses.
- The miners extracted psilomelane from the old manganese mine in the hills.
- Psilomelane is often used in the production of steel to add hardness.
- Collectors value psilomelane for its smooth, shiny black surface.