Nickel is a naturally occurring element that exists in nature mainly in the form of sulfide, oxide, and silicate minerals. Because it is ubiquitous, humans are constantly exposed to nickel in various amounts. “Zero exposure” to nickel is neither possible nor desirable. Nickel has been shown to be an essential element in certain micro- organisms, animals, and plants. The generally held view is that nickel is probably an essential element for humans as well.
Nickel is an extremely important commercial element. Factors which make nickel and its alloys valuable commodities include strength, corrosion resistance, high ductility, good thermal and electric conductivity, magnetic characteristics, and catalytic properties. Stainless steels are particularly valued for their hygienic properties. In some applications, nickel alloys are essential and cannot be substituted with other materials. Given these many beneficial properties, nickel is used in a wide variety of products discussed below.