Black cobalt(III) oxide (Co 2O 3) is also known. At temperatures of 600–700 ☌, CoO oxidizes to the blue cobalt(II,III) oxide (Co 3O 4), which has a spinel structure. It is readily oxidized with water and oxygen to brown cobalt(III) hydroxide (Co(OH) 3). Green cobalt(II) oxide (CoO) has rocksalt structure. In a borax bead flame test, cobalt shows deep blue in both oxidizing and reducing flames. Addition of chloride gives the intensely blue [CoCl These salts form the pink-colored metal aquo complex [Co(H A common oxidation state for simple compounds is +2 (cobalt(II)). Compounds Ĭommon oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are also known. At ordinary temperatures, it reacts slowly with mineral acids, and very slowly with moist, but not dry, air. It does not react with hydrogen gas ( H 2) or nitrogen gas ( N 2) even when heated, but it does react with boron, carbon, phosphorus, arsenic and sulfur. The metal reacts with fluorine (F 2) at 520 K to give CoF 3 with chlorine (Cl 2), bromine (Br 2) and iodine (I 2), producing equivalent binary halides. Heating in oxygen produces Co 3O 4 which loses oxygen at 900 ☌ (1,650 ☏) to give the monoxide CoO. Ĭobalt is a weakly reducing metal that is protected from oxidation by a passivating oxide film. The ideal transition temperature between the hcp and fcc structures is 450 ☌ (842 ☏), but in practice the energy difference between them is so small that random intergrowth of the two is common. Metallic cobalt occurs as two crystallographic structures: hcp and fcc. Cobalt has a relative permeability two-thirds that of iron. The Curie temperature is 1,115 ☌ (2,039 ☏) and the magnetic moment is 1.6–1.7 Bohr magnetons per atom. Cobalt in inorganic form is also a micronutrient for bacteria, algae, and fungi.Ĭharacteristics A block of electrolytically refined cobalt (99.9% purity) cut from a large plateĬobalt is a ferromagnetic metal with a specific gravity of 8.9. Vitamin B 12, the best-known example of the type, is an essential vitamin for all animals. Ĭobalt is the active center of a group of coenzymes called cobalamins. This is to clean it of its sulfur content, which is very polluting when burned and causes acid rain. Cobalt is also used in the petroleum industry as a catalyst when refining crude oil. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays.
Cobalt occurs naturally as only one stable isotope, cobalt-59. The compounds cobalt silicate and cobalt(II) aluminate (CoAl 2O 4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Ĭobalt is primarily used in lithium-ion batteries, and in the manufacture of magnetic, wear-resistant and high-strength alloys. World production in 2016 was 116,000 tonnes (114,000 long tons 128,000 short tons) (according to Natural Resources Canada), and the DRC alone accounted for more than 50%.
The Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. The element is, however, more usually produced as a by-product of copper and nickel mining. Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold. Miners had long used the name kobold ore ( German for goblin ore) for some of the blue pigment-producing minerals they were so named because they were poor in known metals and gave off poisonous arsenic-containing fumes when smelted.
#Cristar cobalt glasses free#
The free element, produced by reductive smelting, is a hard, lustrous, silvery metal.Ĭobalt-based blue pigments ( cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was for a long time thought to be due to the known metal bismuth. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. Cobalt is a chemical element with the symbol Co and atomic number 27.
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