Any form of money can be minted into Monetary Units: packaged units of money of specific quantity and quality. The Monetary Unit is a reliable and convenient store of value, simplifying the valuation and logistical process of barter. The Minter guarantees the content of each Monetary Unit, such as a stamp, and keeps a portion of the minted material, called seigniorage, to cover the expense of minting.
The Monetary Unit is equivalent to a standard weight and measure. A meter is a fixed length, and a liter is a fixed volume. Once defined, the standard should never change. A changing standard is societally disruptive. As an example, if the meter or yard were to be redefined, the impact upon science, engineering, and the trades would be severely disruptive. In the same manner and same magnitude, redefining the Monetary Unit disrupts comparative valuations, negatively impacting the Market and Society.
The minting of money is very ancient in origin.
Moses, Prince of Egypt by Howard Fast (Fictional History)
Yet a sort of money there had to be, and among the Phoenicians pearls and precious stones became the units of trade and measure. The Sea Rovers of the Achaean islands used balls of tin and gold and silver, and the people of Hatti used the most precious metal man had ever found, iron, in cubit-long bars. Among the Egyptians, yardage of linen and sacks of wheat had become too cumbersome for the ever growing commerce of the City of the Ramses, and finger-rings and bracelets of copper, tin and gold were becoming set units of value. Nowhere on all the known earth was there a place where the Egyptian ring had not found its way, and there was no movable product of the earth that had not been unloaded at the stone docks of Ramses.
The legacy of the ancient metals as forms of money lingers today in modern coins. Such pieces of metal have been excavated in Troy, Asia Minor, Babylonia, Assyria, Syria, Egypt, and Iran. The first public building constructed by the new government of the United States, well before the Capitol or White House, was the Mint.