Iron is taken from the earth, and copper is smelted from ore.
Here Job shows, 1. What a great way the wit of man may go in diving into the depths of nature and seizing the riches of it, what a great deal of knowledge and wealth men may, by their ingenious and industrious searches, make themselves masters of.
Commenting on Job 28:1-11
Iron is taken out of the earth,.... Very easily, and in great plenty, and is more common, being in most countries, is nearer the surface of the earth, and here said to be taken "out of the dust" (x); which, being melted in a furnace, produces iron, a metal very serviceable for various rises, and without which there is scarce any thing to be done...
brass--that is, copper; for brass is a mixed metal of copper and zinc, of modern invention. Iron is less easily discovered, and wrought, than copper; therefore copper was in common use long before iron. Copper-stone is called "cadmium" by PLINY [Natural History, 34:1; 36:21]. Iron is fitly said to be taken out of the "earth" (dust), for ore looks like mere earth.