Chemical element chemical bonds, they form chemical compounds. Only a minority of elements are found uncombined as relatively pure minerals. Among the more common of such native elements are copper, silver, gold, carbon (as coal, graphite, or diamonds), and sulfur. All but a few of the most inert elements, such as noble gases and noble metals, are usually found on Earth in chemically combined form, as chemical compounds. While about 32 of the chemical elements occur on Earth in native uncombined forms, most of these occur as mixtures. For example, atmospheric air is primarily a mixture of nitrogen, oxygen, and argon, and
Cobalt(II) oxide Cobalt(II) oxide Cobalt(II) oxide or cobalt monoxide is an inorganic compound that appears as olive-green to red crystals, or as a greyish or black powder. It is used extensively in the ceramics industry as an additive to create blue colored glazes and enamels as well as in the chemical industry for producing cobalt(II) salts. CoO crystals adopt the periclase (rock salt) structure with a lattice constant of 4.2615 Å. It is antiferromagnetic below 16 °C. Cobalt(II,III) oxide decomposes to cobalt(II) oxide at 950 °C: Though commercially available, cobalt(II) oxide may be prepared in the laboratory by electrolyzing a solution of