Nickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four elements that are ferromagnetic around room temperature, the other three being iron, cobalt and gadolinium.
The use of nickel has been traced as far back as 3500 BC, but it was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt, who initially mistook its ore for a copper mineral. Its most important ore minerals are laterites, including limonite and garnierite, and pentlandite. Major production sites include Sudbury region in Canada, New Caledonia and Norilsk in Russia.
Pure nickel shows a significant chemical activity, but is slow to react at ambient conditions due to the formation of a protective oxide surface – similar to some other metals like chromium, aluminium and titanium. Because of this permanence in air and slow rate of oxidation, nickel is considered corrosion-resistant.
Historically it has been used for plating metals such as iron and brass, for chemical apparatus, and in certain alloys such as German silver. About 6% of world nickel production is still used for corrosion-resistant pure-nickel plating. Nickel was a common component of coins, but is has largely been replaced by cheaper iron for this purpose, especially since the metal has proven to be an skin allergen for some people.
Nickel is chiefly valuable in the modern world for the alloys it forms. About 60% of world production is used in nickel-steels (particularly stainless steel). Other common alloys, as well as some new superalloys, make up most of the remainder of world nickel use, with chemical uses for nickel compounds consuming less than 3% of production.
As a compound, nickel has a number of niche chemical manufacturing uses, such as a catalyst for hydrogenation. Enzymes of some microorganisms and plants contain nickel as an active center, which makes the metal an essential nutrient for them. Source www.wikipedia.org