The U.S. Copper Penny is actually composed of 97.5% zinc and only a thin copper coating.
Reference: U.S. Mint
Galvanizing is the practice of immersing clean, oxide-free iron or steel into molten zinc in order to form a zinc coating that is metallurgically bonded to the iron or steel's surface. The zinc coating protects the surface against corrosion by providing protection to the iron or steel in two ways.
Even if the surface becomes scratched and the base metal is exposed, the zinc is slowly consumed while the iron or steel remains protected from corrosion.
The hot dip galvanizing process is adaptable to coating nearly all types of fabricated and non-fabricated products such as wire, tanks, sheets, strip, pipes and tubes, fittings, hardware, wire cloth, hollow-ware, and structural assemblies.
All galvanizing consists of four fundamental steps:
The preparation steps consist of cleaning and pickling operations that free the surface of dirt, grease, rust and scale. The preflux step serves to dissolve any oxide that may have formed on the iron or steel surface after pickling and prevents further rust from forming. Clean, oxide-free work is galvanized by immersion into molten zinc. Finishing operations include quenching, removing excess zinc and inspection.