Isaiah 41:7 So the metal-worker put heart into the gold-worker, and he who was hammering the metal smooth said kind words to the iron-worker, saying of the plate, It is ready: and he put it together with nails, so that there might be no slipping. (See NAS)
Malachi 3:3 and he will sit as a refiner and purifier of silver, and he will purify the sons of Levi, and refine them as gold and silver; and they shall offer to Yahweh offerings in righteousness. (See NAS)