[2] In contrast to noble metals, base metals may be distinguished by oxidizing or corroding relatively easily and reacting variably with diluted hydrochloric acid (HCl) to form hydrogen.
Examples include iron, nickel, lead and zinc.
Copper is also considered a base metal because it oxidizes relatively easily, although it does not react with HCl.
[3] The U.S. Customs and Border Protection agency is more inclusive in its definition of commercial base metals.
Its list includes—in addition to copper, lead, nickel, and zinc—the following metals: iron and steel (an alloy), aluminium, tin, tungsten, molybdenum, tantalum, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium, and thallium, and their alloys.