Metallism via Wikipedia

Metallism is a centuries old school of thought which holds that money derives its value from precious metals. In some older monetary system based on metallism, silver, gold or other metals are used as the primary forms of money. Coins made of officially recognised valuable metal will often be the legal tender.

Especially since the 19th century, adherents of metallism tend to accept that the relationship between money and precious metal can be indirect. In the gold standard adopted by much of the world in the late 19th and early 20th century, various paper bank notes could be exchanged for gold at banks.

Contradistinctions
Metallism versus fiat monetary systems

Adherents of Metallism are opposed to the use of fiat money, i.e. governmentally-issued money with no intrinsic value.
Metallism versus Chartalism

Historically, the main rival school of though to metallism has been Chartalism, which holds that even in systems where coins are made of precious metals, money derives its value mainly from the authority of the State. Competition between these two alternative systems has existed for millennia, long before the concepts were formulised. And in some periods and regions hybrid monetary systems were used. As a set of principles governing the operation of monetary systems, chartalism has existed for several millennia before it was formalised. For example, Constantina Katsari has argued that principles from both metallism and chartalism were reflected in the monetary system introduced by Augustus, which was used in the eastern provinces of Roman Empire, from the early 1st century to the late 3rd century AD [1][2]
Monometallism versus bimetallism

A smaller disagreement which takes place relating to metallism is whether one metal should be used as currency (as in monometallism), or should there be two or more metals for that purpose (as in bimetallism).
History of metalic monetary systems

Historically, silver has been the main kind of money around the world, circulating bimetallically with gold. In many languages, the words for "money" and "silver" are identical. In the final era of global metal-based money, i.e. the first quarter of the 20th century, monometallic gold use has been the standard.
Broad sense of the term

In the broad sense of the term, which tends to be used only by scholars, metallism considers money to be a "creature of the market", a means to facilitate exchange of goods and services. In this broad sense, the essential nature of money is purchasing power, and it does not necessarily need to be backed by metals. Understood in this broad sense, metallism reflects the majority view among mainstream economists, which has prevailed since the early 19th century.[1]