The Wealth of Nations by Part 1 Chapter 5 Page 28

copper.

The northern nations who established themselves upon the ruins of the Roman empire, seem to have had silver money from the first beginning of their settlements, and not to have known either gold or copper coins for several ages thereafter. There were silver coins in England in the time of the Saxons; but there was little gold coined till the time of Edward III nor any copper till that of James I of Great Britain. In England, therefore, and for the same reason, I believe, in all other modern nations of Europe, all accounts are kept, and the value of all goods and of all estates is generally computed in silver: and when we mean to express the amount of a person’s fortune, we seldom mention the number of guineas, but the number of pounds sterling which we suppose would be given for it.