4- or 6- coordinate, although 5-coordinate complexes are known. zinc(i) compounds zinc(i) compounds are very rare. the 2+ ion is implicated by the formation of a yellow diamagnetic glass by dissolving metallic zinc in molten zncl2. the 2+ core would be analogous to the 2+ cation present in mercury(i) compounds. the diamagnetic nature of the ion confirms its dimeric structure. the first zinc(i) compound containing the zn–zn bond, (η5-c5me5)2zn2. zinc(ii) compounds zinc acetate, zn(ch3co2)2 zinc chloride binary compounds of zinc are known for most of the metalloids and all the nonmetals except the noble gases. the oxide zno is a white powder that is nearly insoluble in neutral aqueous solutions, but is amphoteric, dissolving in both strong basic and acidic solutions. the other chalcogenides (zns, znse, and znte) have varied applications in electronics and optics. pnictogenides (zn3n2, zn3p2, zn3as2 and zn3sb2), the peroxide (zno2), the hydride (znh2), and the carbide (znc2) are also known. of the four halides, znf2 has the most ionic character, while the others (zncl2, znbr2, and zni2) have relatively low melting points and are considered to have more covalent character. in weak basic solutions containing zn2+ ions, the hydroxide zn(oh)2 forms as a white precipitate. in stronger alkaline solutions, this hydroxide is dissolved to form zincates (2−). the nitrate zn(no3)2, chlorate zn(clo3)2, sulfate znso4, phosphate zn3(po4)2, molybdate znmoo4, cyanide zn(cn)2, arsenite zn(aso2)2, arsenate zn(aso4)2·8h2o and the chromate zncro4 (one of the few colored zinc compounds) are a few examples of other common inorganic compounds of zinc. organozinc compounds are those that contain zinc–carbon covalent bonds. diethylzinc ((c2h5)2zn) is a reagent in synthetic chemistry. it was first reported in 1848 from the reaction of zinc and ethyl iodide, and was the first compound known to contain a metal–carbon sigma bond. test for zinc cobalticyanide paper (rinnmann's test for zn) can be used as a chemical indicator for zinc. 4 g of k3co(cn)6 and 1 g of kclo3 is dissolved on 100 ml of water. paper is dipped in the solution and dried at 100 °c. one drop of the sample is dropped onto the dry paper and heated. a green disc indicates the presence of zinc. history ancient use the charaka samhita, thought to have been written between 300 and 500 ad, mentions a metal which, when oxidized, produces pushpanjan, thought to be zinc oxide. zinc mines at zawar, near udaipur in india, have been active since the mauryan period (c. 322 and 187 bce). the smelting of metallic zinc here, however, appears to have begun around the 12th century ad. one estimate is that this location produced an estimated million tonnes of metallic zinc and zinc oxide from the 12th to 16th centuries. another estimate gives a total production of 60,000 tonnes of metallic zinc over this period. the rasaratna samuccaya, written in approximately the 13th century ad, mentions two types of zinc-containing ores: one used for metal extraction and another used for medicinal purposes. late roman brass bucket – the hemmoorer eimer from warstade, germany, second to third century ad various isolated examples of the use of impure zinc in ancient times have been discovered. zinc ores were used to make the zinc–copper alloy brass thousands of years prior to the discovery of zinc as a separate element. judean brass from the 14th to 10th centuries bc contains 23% zinc. knowledge of how to produce brass spread to ancient greece by the 7th century bc, but few varieties were made. ornaments made of alloys containing 80–90% zinc, with lead, iron, antimony, and other metals making up the remainder, have been found that are 2,500 years old. a possibly prehistoric statuette containing 87.5% zinc was found in a dacian archaeological site. the oldest known pills were made of the zinc carbonates hydrozincite and smithsonite. the pills were used for sore eyes and were found aboard the roman ship relitto del pozzino, wrecked in 140 bc. the manufacture of brass was known to the romans by about 30 bc. they made brass by heating powdered calamine (zinc silicate or carbonate), charcoal and copper together in a crucible. the resulting calamine brass was then either cast or hammered into shape for use in weaponry. some coins struck by romans in the christian era are made of what is probably calamine brass. strabo writing in the 1st century bc (but quoting a now lost work of the 4th century bc historian theopompus) mentions "drops of false silver" which when mixed with copper make brass. this may refer to small quantities of zinc that is a by-product of smelting sulfide ores. zinc in such remnants in smelting ovens was usually discarded as it was thought to be worthless. the berne zinc tablet is a votive plaque dating to roman gaul made of an alloy that is mostly zinc. early studies and naming zinc was distinctly recognized as a metal under the designation of yasada or jasada in the medical lexicon ascribed to the hindu king madanapala (of taka dynasty) and written about the year 1374. smelting and extraction of impure zinc by reducing calamine with wool and other organic substances was accomplished in the 13th century in india. the chinese did not learn of the technique until the 17th century. alchemical symbol for the element zinc alchemists burned zinc metal in air and collected the resulting zinc oxide on a condenser. some alchemists called this zinc oxide lana philosophica, latin for "philosopher's wool", because it collected in wooly tufts, whereas others thought it looked like white snow and named it nix album. the name of the metal was probably first documented by paracelsus, a swiss-born german alchemist, who referred to the metal as "zincum" or "zinken" in his book liber mineralium ii, in the 16th century. the word is probably derived from the german zinke, and supposedly meant "tooth-like, pointed or jagged" (metallic zinc crystals have a needle-like appearance). zink could also imply "tin-like" because of its relation to german zinn meaning tin. yet another possibility is that the word is derived from the persian word سنگ seng meaning stone. the metal was also called indian tin, tutanego, calamine, and spinter. german metallurgist andreas libavius received a quantity of what he called "calay" of malabar from a cargo ship captured from the portuguese in the year 1596. libavius described the properties of the sample, which may have been zinc. zinc was regularly imported to europe from the orient in the 17th and early 18th centuries, but was at times very expensive. isolation andreas sigismund marggraf is given credit for first isolating pure zinc metallic zinc was isolated in india by 1300 ad, much earlier than in the west. before it was isolated in europe, it was imported from india in about 1600 ce. postlewayt's universal dictionary, a contemporary source giving technological information in europe, did not mention zinc before 1751 but the element was studied before then. flemish metallurgist and alchemist p. m. de respour reported that he had extracted metallic zinc from zinc oxide in 1668. by the start of the 18th century, étienne françois geoffroy described how zinc oxide condenses as yellow crystals on bars of iron placed above zinc ore that is being smelted. in britain, john lane is said to have carried out experiments to smelt zinc, probably at landore, prior to his bankruptcy in 1726. in 1738 in great britain, william champion patented a process to extract zinc from calamine in a vertical retort-style smelter. his technique resembled that used at zawar zinc mines in rajasthan, but no evidence suggests he visited the orient. champion's process was used through 1851. german chemist andreas marggraf normally gets credit for discovering pure metallic zinc, even though swedish chemist anton von swab had distilled zinc from calamine four years previously. in his 1746 experiment, marggraf heated a mixture of calamine and charcoal in a closed vessel without copper to obtain a metal. this procedure became commercially practical by 1752. later work galvanization was named after luigi galvani. william champion's brother, john, patented a process in 1758 for calcining zinc sulfide into an oxide usable in the retort process. prior to this, only calamine could be used to produce zinc. in 1798, johann christian ruberg improved on the smelting process by building the first horizontal retort smelter. jean-jacques daniel dony built a different kind of horizontal zinc smelter in belgium that processed even more zinc. italian doctor luigi galvani discovered in 1780 that connecting the spinal cord of a freshly dissected frog to an iron rail attached by a brass hook caused the frog's leg to twitch. he incorrectly thought he had discovered an ability of nerves and muscles to create electricity and called the effect "animal electricity". the galvanic cell and the process of galvanization were both named for luigi galvani, and his discoveries paved the way for electrical batteries, galvanization, and cathodic protection. galvani's friend, alessandro volta, continued researching the effect and invented the voltaic pile in 1800. volta's pile consisted of a stack of simplified galvanic cells, each being one plate of copper and one of zinc connected by an electrolyte. by stacking these units in series, the voltaic pile (or "battery") as a whole had a higher voltage, which could be used more easily than single cells. electricity is produced because the volta potential between the two metal plates makes electrons flow from the zinc to the copper and corrode the zinc. the non-magnetic character of zinc and its lack of color in solution delayed discovery of its importance to biochemistry and nutrition. this changed in 1940 when carbonic anhydrase, an enzyme that scrubs carbon dioxide from blood, was shown to have zinc in its active site. the digestive enzyme carboxypeptidase became the second known zinc-containing enzyme in 1955. production mining and processing top zinc mine production output (by countries) 2019 rankcountrytonnes 1china4,210,000 2peru1,400,000 3australia1,330,000 5united states753,000 4india720,000 6mexico677,000 price of zinc percentage of zinc output in 2006 by countries world production trend zinc mine rosh pinah, namibia27°57′17″s 016°46′00″e zinc mine skorpion, namibia27°49′09″s 016°36′28″e zinc is the fourth most common metal in use, trailing only iron, aluminium, and copper with an annual production of about 13 million tonnes. the world's largest zinc producer is nyrstar, a merger of the australian oz minerals and the belgian umicore. about 70% of the world's zinc originates from mining, while the remaining 30% comes from recycling secondary zinc. commercially pure zinc is known as special high grade, often abbreviated shg, and is 99.995% pure. worldwide, 95% of new zinc is mined from sulfidic ore deposits, in which sphalerite (zns) is nearly always mixed with the sulfides of copper, lead and iron.: 6 zinc mines are scattered throughout the world, with the main areas being china, australia, and peru. china produced 38% of the global zinc output in 2014. zinc metal is produced using extractive metallurgy.: 7 the ore is finely ground, then put through froth flotation to separate minerals from gangue (on the property of hydrophobicity), to get a zinc sulfide ore concentrate: 16 consisting of about 50% zinc, 32% sulfur, 13% iron, and 5% sio2.: 16 roasting converts the zinc sulfide concentrate to zinc oxide: 2 zns + 3 o 2 → t o 2 zno + 2 so 2 the sulfur dioxide is used for the production of sulfuric acid, which is necessary for the leaching process. if deposits of zinc carbonate, zinc silicate, or zinc-spinel (like the skorpion deposit in namibia) are used for zinc production, the roasting can be omitted. for further processing two basic methods are used: pyrometallurgy or electrowinning. pyrometallurgy reduces zinc oxide with carbon or carbon monoxide at 950 °c (1,740 °f) into the metal, which is distilled as zinc vapor to separate it from other metals, which are not volatile at those temperatures. the zinc vapor is collected in a condenser. the equations below describe this process: zno + c → 950 o c zn + co zno + co → 950 o c zn + co 2 in electrowinning, zinc is leached from the ore concentrate by sulfuric acid and impurities are precipitated: zno + h 2 so 4 ⟶ znso 4 + h 2 o finally, the zinc is reduced by electrolysis. 2 znso 4 + 2 h 2 o ⟶ 2 zn + o 2 +