| Answer | Crossword Clue |
|---|---|
| NIOBIUM | Its principal ore is columbite |
| coltan | a dull black ore that consists of a mixture of columbite and tantalite and is a minor source of tantalum |
| chalcopyrite | A yellow crystalline mineral consisting of a sulfide of copper and iron. It is the principal ore of copper |
| pentlandite | A bronze-yellow mineral that consists of a sulfide of iron and nickel and is the principal ore of nickel |
| MORAVIA | Brno is its principal city |
| RUHR | Its principal city is Essen |
| ELBA | Portoferraio is its principal port |
