The antiquity of certain mining operations has also been much exaggerated. A very late writer has imagined, that the mines of the island of Elba, judging from the rubbish carried out of them, must have been wrought for more than 40,000 years; but another author, who has also examined this rubbish with attention, has reduced the period in question to a little more than 5000 years,[243] and this even on the supposition that the ancients did not extract annually more than a fourth part of the quantity of ore now wrought. But what reason could there be to suppose that the Romans, for example, who consumed so much iron in their armies, derived so little advantage from these mines? Moreover, if these mines had been wrought for even 4000 years only, how should iron have been so little known in the times of remote antiquity?