| Rating | Solver | Clue |
|---|---|---|
| MAGNETITE | Black iron oxide | |
| CHROMITE | A black submetallic mineral consisting of oxide of chromium and iron; -- called also chromic iron. | |
| PSILOMELANE | A hydrous oxide of manganese, occurring in smooth, botryoidal forms, and massive, and having an iron-black or steel-gray color. | |
| WADD | An earthy oxide of manganese, or mixture of different oxides and water, with some oxide of iron, and often silica, alumina, lime, or baryta; black ocher. There are several varieties. |