Iron was the only metal that could kill the Fae.

Mercury is the only metal that is a liquid at room temperature.

Gold is not the only precious metal on the up.

Copper then was the only metal known to man for a long period of time.

The only other metal in common use that has a non-gray color is copper.

Silver is said to be the only metal to pierce its magic invulnerability.

Mercury is the only metal with a known melting point ( 38.83 C) lower than caesium.

The only hard metal in it otherwise is the jets themselves.

The only metal was the detonator, too small to be picked up by mine detectors.

Perhaps copper was the only metal available at the time.