Strabo, Geography
H.C. Hamilton, Esq., W. Falconer, M.A., Ed.

Polybius, speaking of the silver mines of New Carthage,¹ tells us that they are extremely large, distant from the city about 20 stadia, and occupy a circuit of 400 stadia, that there are 40,000 men regularly engaged in them, and that they yield daily to the Roman people [a revenue of] 25,000 drachmæ. The rest of the process I pass over, as it is too long, but as for the silver ore collected, he tells us that it is broken up, and sifted through sieves over water; that what remains is to be again broken, and the water having been strained off, it is to be sifted and broken a third time. The dregs which remain after the fifth time are to be melted, and the lead being poured off, the silver is obtained pure. These silver mines still exist; however they are no longer the property of the state, neither these nor those elsewhere, but are possessed by private individuals. The gold mines, on the contrary, nearly all belong to the state. Both at Castlon² and other places there are singular lead mines worked. They contain a small proportion of silver, but not sufficient to pay for the expense of refining.