Cobalt is a chemical element with the symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron; the free element, produced by reductive smelting, is a hard, silver-gray metal. Cobalt-based blue pigments have been used since ancient times for jewelry and paints, to impart a distinctive blue tint to glass, but the color was thought to be due to the known metal bismuth. Miners had long used the name kobold ore for some of the blue-pigment-producing minerals. In 1735, such ores were found to be reducible to a new metal, this was named for the kobold. Today, some cobalt is produced from one of a number of metallic-lustered ores, such as cobaltite; the element is, more produced as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo and Zambia yields most of the global cobalt production. World production in 2016 was 116,000 tonnes, the DRC alone accounted for more than 50%.
Cobalt is used in lithium-ion batteries, in the manufacture of magnetic, wear-resistant and high-strength alloys. The compounds cobalt silicate and cobalt aluminate give a distinctive deep blue color to glass, inks and varnishes. Cobalt occurs as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays. Cobalt is the active center of a group of coenzymes called cobalamins. Vitamin B12, the best-known example of the type, is an essential vitamin for all animals. Cobalt in inorganic form is a micronutrient for bacteria and fungi. Cobalt is a ferromagnetic metal with a specific gravity of 8.9. The Curie temperature is 1,115 °C and the magnetic moment is 1.6–1.7 Bohr magnetons per atom. Cobalt has a relative permeability two-thirds. Metallic cobalt occurs as two crystallographic structures: fcc; the ideal transition temperature between the hcp and fcc structures is 450 °C, but in practice the energy difference between them is so small that random intergrowth of the two is common.
Cobalt is a weakly reducing metal, protected from oxidation by a passivating oxide film. It is attacked by halogens and sulfur. Heating in oxygen produces Co3O4 which loses oxygen at 900 °C to give the monoxide CoO; the metal reacts with fluorine at 520 K to give CoF3. It does not react with hydrogen gas or nitrogen gas when heated, but it does react with boron, phosphorus and sulfur. At ordinary temperatures, it reacts with mineral acids, slowly with moist, but not with dry, air. Common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are known. A common oxidation state for simple compounds is +2; these salts form the pink-colored metal aquo complex 2+ in water. Addition of chloride gives the intensely blue 2−. In a borax bead flame test, cobalt shows deep blue in both reducing flames. Several oxides of cobalt are known. Green cobalt oxide has rocksalt structure, it is oxidized with water and oxygen to brown cobalt hydroxide. At temperatures of 600 -- 700 °C, CoO oxidizes to the blue cobalt oxide.
Black cobalt oxide is known. Cobalt oxides are antiferromagnetic at low temperature: CoO and Co3O4, analogous to magnetite, with a mixture of +2 and +3 oxidation states; the principal chalcogenides of cobalt include the black cobalt sulfides, CoS2, which adopts a pyrite-like structure, cobalt sulfide. Four dihalides of cobalt are known: cobalt fluoride, cobalt chloride, cobalt bromide, cobalt iodide; these halides exist in hydrated forms. Whereas the anhydrous dichloride is blue, the hydrate is red; the reduction potential for the reaction Co3+ + e− → Co2+ is +1.92 V, beyond that for chlorine to chloride, +1.36 V. Consequently and chloride would result in the cobalt being reduced to cobalt; because the reduction potential for fluorine to fluoride is so high, +2.87 V, cobalt fluoride is one of the few simple stable cobalt compounds. Cobalt fluoride, used in some fluorination reactions, reacts vigorously with water; as for all metals, molecular compounds and polyatomic ions of cobalt are classified as coordination complexes, that is, molecules or ions that contain cobalt linked to several ligands.
The principles of electronegativity and hardness–softness of a series of ligands can be used to explain the usual oxidation state of cobalt. For example, Co3+ complexes tend to have ammine ligands; because phosphorus is softer than nitrogen, phosphine ligands tend to feature the softer Co2+ and Co+, an example being triscobalt chloride. The more electronegative oxide and fluoride can stabilize Co4+ and Co5+ derivatives, e.g. caesium hexafluorocobaltate and potassium percobaltate. Alfred Werner, a Nobel-prize winning pioneer in coordination chemistry, worked with compounds of empirical formula 3+. One o
Marcel Pepin was a trade unionist in Quebec, Canada. He was the president of the Confédération des syndicats nationaux from 1965 until 1976. Pepin graduated with a master's degree in industrial relations from the faculty of social sciences at the Université Laval in 1949, he became negotiator for the textile workers and steelworkers federations of the CTCC. In 1961 he became the secretary general of the Confédération des syndicats nationaux. In 1965, he was elected president of the CSN, succeeding to Jean Marchand, who had left the CSN to join the Liberal Party of Canada. During Pepin's tenure as president, the CSN moved toward more radical orientations. In 1972, the three major labour federations of Quebec temporarily concerted their forces into a "common front" during negotiations with the government of Robert Bourassa. In 1976, Pepin was succeeded by Norbert Rodrigue as president of the CSN. Pepin was president of the World Confederation of Labour from 1973 until 1981. From 1980 until 1990 Pepin taught at the school of industrial relations of the Université de Montréal.
He retired in 1990. In 1979, Pepin and other trade unionists and academics published a manifesto for the creation of a socialist movement and in 1981 they founded a left-wing political party, the Mouvement socialiste; that party ran ten candidates in the 1985 and 1989 Quebec general elections, but it remained marginal and was dissolved around 1991. He was married to Lucie Dagenais, he had five children
Dhekiakhowa Bornaamghar is a naamghar in Jorhat district, India, established by saint-reformer Madhavdeva. He kindled an earthen lamp there, continuously burning since 1528,being religiously refuelled with mustard oil by the priests till date, it is located at Dhekiakhowa village of Jorhat district, 15 km towards the east of Jorhat city 3.5 km away from National Highway 37. It is called a Bornaamghar because of large campus; the naamghar is situated in a complex of facilities spread over 13 bighas of land. The naamghar and other facilities are maintained by a managing committee with donations from devotees. Besides the maintenance of the complex, the managing committee sponsors various social and cultural programs. There is an anecdote after the name of Dhekiakhowa Naamghar. Guru Madhavdeva after taking up the duty of reforming people and spreading the Ekasarana Nam Dharma came to stay in this small and poor village, he took shelter for the night at the hut of an old woman. The old woman was embarrassed to have served the Saint guru like this but he was immensely pleased by the dinner.
So he started a namghar there and given the responsibility of kindling the earthen lamp to the old woman. That is why the naamghar was known as Dhekiakhowa Naamghar; the place is named after the Naamghar itself. A lot of visitors and devotees gather in the naamghar everyday during the sacred month of Bhado, for this month being the Death Anniversaries of both the gurus Srimanta Sankardeva and Madhavdeva There are many stories associated with this Bornaamghar, it is said. One night one of the bhakats of the naamghar saw in his dream that the river near the Bornaamghar is flowing in opposite direction and is carrying a Sal tree mean to be for the construction of the Bor namghar. Next day when people saw that dream to be true, they made the main pillers of the Bornaamghar from the tree. A Vaishnavite lamp in Dhekiakhowa Bornaamghar is said to have been kept burning since 1528; this could enter itself in the Guinness Book of World Records as the longest lighting lamp. Several festivals and sessions of special worship, besides the daily worships, are celebrated every year in certain months.
These festivities are attended by lakhs of devotees - 1. Paal Naam - a month long festival of worship in the month of Bhada from mid August to mid September. 2. Srimanta Sankardeva birth anniversary during the month of Aahin from mid September to mid October. 3. Madhavdeva birth anniversary during the month of Jeth from 15 May to 15 June. 4. Bhaona Mohotsav in the month of Chot or Chaitra from 15 March to 15 April. 5. Raas lila in the month of November. Https://www.panoramio.com/photo/66233208 http://articles.timesofindia.indiatimes.com/2012-06-14/guwahati/32234193_1_lamp-flame-jorhat