Commodity money cans or foil pouches of mackerel fish fillets, which have a fairly standard cost and are easy to store. These may be exchanged for many services in prisons where personal possession of currency is prohibited. In situations where the commodity is metal, typically gold or silver, a government mint will often coin money by placing a mark on the metal that serves as a guarantee of the weight and purity of the metal. In doing so, the government will often impose a fee which is known as seigniorage. The role of a mint and of coin differs between commodity money
Commodity pathway diversion seen as a commodity by one person and something else by another. Such shifts and differences in whether and when a thing is a commodity reveal a moral economy that stands behind the objective economy of visible transactions. In his discussion of commoditization, he also presents the idea of singularization which occurs because "there are things that are publicly precluded from being commoditized…[and are] sometimes extended to things that are normally commodities—in effect, commodities are singularized by being pulled out of their commodity sphere." Kopytoff goes on to describe ways in which commodities can be singularized, for example, through restricted