Fungibility Fungibility In economics, fungibility is the property of a good or a commodity whose individual units are essentially interchangeable. For example, since one kilogram of pure gold is equivalent to any other kilogram of pure gold, whether in the form of coins, ingots, or in other states, gold is fungible. Other fungible commodities include sweet crude oil, company shares, bonds, other precious metals, and currencies. Fungibility refers only to the equivalence of each unit of a commodity with other units of the same commodity and not to the exchange of one commodity for another, which is barter. The word "fungibility"
Commodity (Marxism) of value, product-values in an open market are regulated by the average socially necessary labour time required to produce them, and price relativities of products are ultimately governed by the law of value. Commodity-trade, Marx argues, historically begins at the boundaries of separate economic communities based otherwise on a "non-commercial" form of production. Thus, producers trade in those goods of which those producers, have episodic or permanent surpluses to their own requirements, and they aim to obtain different goods with an equal value in return. Marx refers to this as "simple exchange" which implies what Frederick Engels calls "simple commodity