In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid (HCl) to form hydrogen. Examples include iron, nickel, lead and zinc. Copper is considered a base metal as it oxidizes relatively easily, although it does not react with HCl.
Base is used in the sense of low-born, in opposition to noble or precious metal. In alchemy, a base metal was a common and inexpensive metal, as opposed to precious metals, mainly gold and silver. A long-time goal of the alchemists was the transmutation of base metal into precious metal.
In numismatics, coins used to derive their value primarily from the precious metal content. Most modern currencies are fiat currency, allowing the coins to be made of base metal.
In mining and economics, base metals refers to industrial non-ferrous metals excluding precious metals. These include copper, lead, nickel and zinc. The U.S. Customs and Border Protection is more inclusive in its definition. It includes, in addition to the four above, iron and steel, aluminium, tin, tungsten, molybdenum, tantalum, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium and thallium.
In the context of plated metal products, the base metal underlies the plating metal, as copper underlies silver in Sheffield plate.
Famous quotes containing the words base and/or metal:
“It is a base thing for a man among the people not to obey those in command. Never in a state can the laws be well administered when fear does not stand firm.”
—Sophocles (497–406/5 B.C.)
“There were metal detectors on the staff-room doors and Hernandez usually had a drawer full of push-daggers, nunchuks, stun-guns, knucks, boot-knives, and whatever else the detectors had picked up. Like Friday morning at a South Miami high school.”
—William Gibson (b. 1948)