Nickel is extracted from ores via the Mond process, in which nickel oxides are purified through multiple steps into pure nickel metal. It is placed with hydrogen and carbon monoxide gases at 122 degrees Fahrenheit, which converts it to impure nickel. This impure nickel then reacts with the carbon monoxide, becoming nickel tetracarbonyl. This is then heated to 446 degrees Fahrenheit, which releases the carbon monoxide gas and leaves pure nickel metal.
Relatively pure coins made of nickel were used as far back as 235 BCE in China, but it was first documented as a unique metal after extraction in 1751. It was initially seen as worthless, but its many uses were soon discovered. Nickel is a very useful metal for making alloys, adding strength, hardness and corrosion resistance. It is used in silver plating, and is a key ingredient in stainless steel, one of the most-used alloys.
While nickel does occur naturally as a pure metal in the form of cubic crystals, it is generally mined from mixed ores. As a pure metal, it is malleable and ductile and has moderate thermal and electrical conductivity. Nickel is also a magnetic metal below 653 degrees Fahrenheit. It is somewhat reactive with dilute nitric, hydrochloric and sulfuric acids.