Metals and Money
Metal is a product of the land, extracted from it by labor in the mines and refined for use. It is different to livestock or plant products in that it cannot be replenished once extracted, but similar in that the labor is applied to extract the value from the land and that the quality of a mine, like the fertility of the soil, determines the quantity of output.
In terms of labor, the miner is better compensated than the farmer because the work is more dangerous and unpleasant. There is also considerable expense in establishing a new mine, and considerable risk in the undertaking - as it is not known how much ore will be produced, if any at all. As such there is great risk and many proprietors are ruined by mining, but there is great reward if the prospect is a success.
All of this contributes to the production cost, hence the price that the producer cares to demand of his product. The price customers are willing to pay is based on the value they will derive from owning it, and competition among buyers for possession a scarce resource, which is entirely indifferent to the cost of production.
Base metals such as tin, copper, iron, and lead are valued for their durability. A pewter dish lasts far longer than one made of earthenware, and a steel shovel is more durable and effective than one made of wood - were it not so these metals would not be much valued, and customers would offer insufficient reward to producers to undertake the expense and risk of producing metal.
Gold and silver are metals of exceptional durability and permanence - they do not corrode and decay as do copper and iron, and were as such greatly valued even before they were used in commercial exchange. Historical records show that Romans prized these metals for useful application at least five hundred years before they were struck into coin.
Additionally, gold and silver are very rare - rarer still in the ancient world because of the lack of sophistication at extracting metal from ore meant that producers must rely on lodes of pure metal. The author speculates that it could be traded in small pieces for items a hundred times its weight.
There is some consideration of the value of gold and silver as a commodity of exchange due to various properties. The metals do not rot or corrode, are easily divisible into small increments, have high value for their weight, etc. It is not surprising that all countries eventually evolved to the use of gold and silver as money.
As such, there was great profit to be made in debasing precious metal, creating an alloy of silver and copper that would be valued as if it were pure silver. To avoid being cheated, merchants were required not only to weigh metal but to test its purity by taking a sample and subjecting it to various methods (head or acids) of separating the precious metal from the base to assess the amount of pure silver they were being offered.
Naturally, the difficult of owing so led to great interest in pieces of metal whose alloy could be trusted - hence coinage, as pieces of metal whose purity and weight was backed by the guarantee of the mint or a government, the falsification of which was punishable by the state.
And, of course, princes are not immune to corruption and have at times perpetrated fraud upon their people by means of debasing their currency - but history shows it is not long before the fraud is uncovered and the nominal price of goods in units of national currency rise in proportion to the debasement of coinage.
Even so, many have been confounded by the value placed on gold and silver, suggesting that their inability to serve a useful purpose should result in their being regarded as useless rather than priceless - and it cannot be denied that the value they have in trade is entirely subjective and, should a given market change its fancy to some other commodity as a means of exchange, precious metals would be mere ornamentation. But such has not been the way of things.