 = Antimony = 
 
 Antimony is a chemical element with symbol Sb ( from Latin : stibium ) and atomic number 51 . A lustrous gray metalloid , it is found in nature mainly as the sulfide mineral stibnite ( Sb2S3 ) . Antimony compounds have been known since ancient times and were used for cosmetics ; metallic antimony was also known , but it was erroneously identified as lead upon its discovery . In the West , it was first isolated by <unk> Biringuccio and described in 1540 , although in primitive cultures its powder has been used to cure eye <unk> , as also for eye shadow , since time immemorial , and is often referred to by its Arabic name , kohl . 
 For some time , China has been the largest producer of antimony and its compounds , with most production coming from the <unk> Mine in <unk> . The industrial methods to produce antimony are roasting and reduction using carbon or direct reduction of stibnite with iron . 
 The largest applications for metallic antimony are as <unk> material for lead and tin and for lead antimony plates in lead – acid batteries . <unk> lead and tin with antimony improves the properties of the alloys which are used in solders , bullets and plain bearings . Antimony compounds are prominent <unk> for chlorine and <unk> @-@ containing fire retardants found in many commercial and domestic products . An emerging application is the use of antimony in <unk> . 
 
 = = Characteristics = = 
 
 
 = = = Properties = = = 
 
 Antimony is in the nitrogen group ( group 15 ) and has an <unk> of 2 @.@ 05 . As expected from periodic trends , it is more electronegative than tin or <unk> , and less electronegative than <unk> or arsenic . Antimony is stable in air at room temperature , but reacts with oxygen if heated , to form antimony trioxide , <unk> . 
 Antimony is a silvery , lustrous gray metalloid that has a <unk> scale hardness of 3 . Thus pure antimony is too soft to make hard objects ; coins made of antimony were issued in China 's <unk> province in 1931 , but because of their rapid wear , their <unk> was discontinued . Antimony is resistant to attack by acids . 
 Four <unk> of antimony are known : a stable metallic form and three metastable forms ( explosive , black and yellow ) . Elemental antimony is a brittle , silver @-@ white <unk> metalloid . When slowly cooled , molten antimony <unk> in a trigonal cell , <unk> with the gray allotrope of arsenic . A rare explosive form of antimony can be formed from the electrolysis of antimony <unk> . When <unk> with a sharp implement , an <unk> reaction occurs and white fumes are given off as metallic antimony is formed ; when rubbed with a <unk> in a mortar , a strong detonation occurs . Black antimony is formed upon rapid cooling of vapor derived from metallic antimony . It has the same crystal structure as red phosphorus and black arsenic , it oxidizes in air and may ignite spontaneously . At 100 ° C , it gradually transforms into the stable form . The yellow allotrope of antimony is the most unstable . It has only been generated by oxidation of stibine ( <unk> ) at − 90 ° C. Above this temperature and in ambient light , this metastable allotrope transforms into the more stable black allotrope . 
 Elemental antimony adopts a layered structure ( space group <unk> No. 166 ) in which layers consist of fused <unk> six @-@ membered rings . The nearest and next @-@ nearest neighbors form an irregular <unk> complex , with the three atoms in the same double layer being slightly closer than the three atoms in the next . This relatively close packing leads to a high density of 6 @.@ 697 g / cm3 , but the weak bonding between the layers leads to the low hardness and <unk> of antimony . 
 
 = = = Isotopes = = = 
 
 Antimony has two stable isotopes : <unk> with a natural abundance of 57 @.@ 36 % and <unk> with a natural abundance of 42 @.@ 64 % . It also has 35 <unk> , of which the longest @-@ lived is <unk> with a half @-@ life of 2 @.@ 75 years . In addition , 29 metastable states have been characterized . The most stable of these is <unk> with a half @-@ life of 5 @.@ 76 days . Isotopes that are lighter than the stable <unk> tend to decay by β + decay , and those that are heavier tend to decay by β − decay , with some exceptions . 
 
 = = = Occurrence = = = 
 
 The abundance of antimony in the Earth 's crust is estimated at 0 @.@ 2 to 0 @.@ 5 parts per million , comparable to <unk> at 0 @.@ 5 parts per million and silver at 0 @.@ 07 ppm . Even though this element is not abundant , it is found in over 100 mineral species . Antimony is sometimes found <unk> ( e.g. on Antimony Peak ) , but more frequently it is found in the sulfide stibnite ( Sb2S3 ) which is the predominant ore mineral . 
 
 = = Compounds = = 
 
 Antimony compounds are often classified according to their oxidation state : Sb ( III ) and Sb ( V ) . The + 5 oxidation state is more stable . 
 
 = = = <unk> and <unk> = = = 
 
 Antimony trioxide ( Sb 
 4O 
 6 ) is formed when antimony is burnt in air . In the gas phase , this compound exists as Sb 
 4O 
 6 , but it <unk> upon <unk> . Antimony <unk> ( Sb 
 4O 
 10 ) can only be formed by oxidation by concentrated nitric acid . Antimony also forms a mixed @-@ valence oxide , antimony tetroxide ( Sb 
 2O 
 4 ) , which features both Sb ( III ) and Sb ( V ) . Unlike oxides of phosphorus and arsenic , these various oxides are <unk> , do not form well @-@ defined <unk> and react with acids to form antimony salts . 
 <unk> acid Sb ( OH ) 
 3 is unknown , but the <unk> base sodium <unk> ( [ Na 
 <unk> 
 3 ] 
 4 ) forms upon fusing sodium oxide and Sb 
 4O 
 6 . Transition metal <unk> are also known . <unk> acid exists only as the hydrate <unk> ( OH ) 
 6 , forming salts containing the <unk> anion Sb ( OH ) − 
 6 . <unk> metal salts containing this anion yields mixed oxides . 
 Many antimony ores are sulfides , including stibnite ( Sb 
 2S 
 3 ) , <unk> ( <unk> 
 <unk> 
 3 ) , <unk> , <unk> , and <unk> . Antimony <unk> is non @-@ stoichiometric and features antimony in the + 3 oxidation state and S @-@ S bonds . Several <unk> are known , such as [ Sb 
 <unk> 
 10 ] 2 − and [ Sb 
 <unk> 
 13 ] 2 − . 
 
 = = = Halides = = = 
 
 Antimony forms two series of halides : <unk> 
 3 and <unk> 
 5 . The <unk> SbF 
 3 , SbCl 
 3 , <unk> 
 3 , and <unk> 
 3 are all molecular compounds having trigonal pyramidal molecular geometry . 
 The <unk> SbF 
 3 is prepared by the reaction of Sb 
 2O 
 3 with HF : 
 Sb 
 2O 
 3 + 6 HF → 2 SbF 
 3 + 3 H 
 2O 
 It is Lewis acidic and readily accepts fluoride ions to form the complex anions SbF − 
 4 and <unk> − 
 5 . <unk> SbF 
 3 is a weak electrical conductor . The <unk> SbCl 
 3 is prepared by dissolving Sb 
 2S 
 3 in <unk> acid : 
 Sb 
 2S 
 3 + 6 <unk> → 2 SbCl 
 3 + 3 H 
 2S 
 The <unk> SbF 
 5 and SbCl 
 5 have trigonal <unk> molecular geometry in the gas phase , but in the liquid phase , SbF 
 5 is <unk> , whereas SbCl 
 5 is <unk> . SbF 
 5 is a powerful Lewis acid used to make the <unk> <unk> acid ( " <unk> " ) . 
 <unk> are more common for antimony than arsenic and phosphorus . Antimony trioxide dissolves in concentrated acid to form <unk> compounds such as <unk> and ( <unk> ) 
 <unk> 
 4 . 
 
 = = = <unk> , <unk> , and <unk> compounds = = = 
 
 Compounds in this class generally are described as derivatives of Sb3 − . Antimony forms antimonides with metals , such as indium antimonide ( <unk> ) and silver antimonide ( <unk> 
 <unk> ) . The alkali metal and zinc antimonides , such as <unk> and <unk> , are more reactive . <unk> these antimonides with acid produces the unstable gas stibine , <unk> 
 3 : 
 Sb3 − + 3 H + → <unk> 
 3 
 <unk> can also be produced by treating Sb3 + salts with hydride reagents such as sodium <unk> <unk> spontaneously at room temperature . Because stibine has a positive heat of formation , it is <unk> unstable and thus antimony does not react with hydrogen directly . 
 <unk> compounds are typically prepared by <unk> of antimony halides with <unk> reagents . A large variety of compounds are known with both Sb ( III ) and Sb ( V ) centers , including mixed <unk> @-@ organic derivatives , anions , and <unk> . Examples include Sb ( C6H5 ) 3 ( <unk> ) , <unk> ( C6H5 ) 4 ( with an Sb @-@ Sb bond ) , and cyclic [ Sb ( C6H5 ) ] n . <unk> <unk> compounds are common , examples being Sb ( C6H5 ) 5 and several related halides . 
 
 = = History = = 
 
 Antimony ( III ) sulfide , Sb2S3 , was recognized in predynastic Egypt as an eye cosmetic ( kohl ) as early as about 3100 BC , when the cosmetic palette was invented . 
 An artifact , said to be part of a vase , made of antimony dating to about 3000 BC was found at <unk> , <unk> ( part of present @-@ day Iraq ) , and a copper object plated with antimony dating between 2500 BC and <unk> BC has been found in Egypt . Austen , at a lecture by Herbert Gladstone in 1892 commented that " we only know of antimony at the present day as a highly brittle and crystalline metal , which could hardly be fashioned into a useful vase , and therefore this remarkable ' find ' ( artifact mentioned above ) must represent the lost art of rendering antimony malleable . " 
 <unk> was <unk> the artifact was indeed a vase , mentioning that <unk> , after his analysis of the <unk> object ( published in 1975 ) , " attempted to relate the metal to <unk> natural antimony " ( i.e. native metal ) and that " the antimony objects from <unk> are all small personal ornaments . " This weakens the evidence for a lost art " of rendering antimony malleable . " 
 The Roman scholar Pliny the Elder described several ways of preparing antimony sulfide for medical purposes in his treatise Natural History . Pliny the Elder also made a distinction between " male " and " female " forms of antimony ; the male form is probably the sulfide , while the female form , which is superior , heavier , and less <unk> , has been suspected to be native metallic antimony . 
 The Roman naturalist <unk> <unk> mentioned that antimony sulfide could be roasted by heating by a current of air . It is thought that this produced metallic antimony . 
 The first description of a procedure for isolating antimony is in the book De la <unk> of 1540 by <unk> Biringuccio ; this predates the more famous <unk> book by <unk> , De re <unk> . In this context <unk> has been often incorrectly credited with the discovery of metallic antimony . The book <unk> <unk> <unk> ( The <unk> Chariot of Antimony ) , describing the preparation of metallic antimony , was published in Germany in 1604 . It was purported to have been written by a Benedictine monk , writing under the name <unk> <unk> , in the 15th century ; if it were authentic , which it is not , it would predate Biringuccio . 
 The metal antimony was known to German chemist Andreas <unk> in 1615 who obtained it by adding iron to a molten mixture of antimony sulfide , salt and potassium tartrate . This procedure produced antimony with a crystalline or starred surface . 
 With the advent of challenges to <unk> theory it was recognized that antimony is an element forming sulfides , oxides , and other compounds , as is the case with other metals . 
 The first natural occurrence of pure antimony in the Earth 's crust was described by the Swedish scientist and local mine district engineer Anton von <unk> in 1783 ; the type @-@ sample was collected from the <unk> Silver Mine in the <unk> mining district of <unk> , <unk> , Sweden . 
 
 = = = Etymology = = = 
 
 The ancient words for antimony mostly have , as their chief meaning , kohl , the sulfide of antimony . 
 The Egyptians called antimony <unk> ; in hieroglyphs , the vowels are uncertain , but there is an Arabic tradition that the word is <unk> <unk> . The Greek word , <unk> stimmi , is probably a loan word from Arabic or from Egyptian <unk> 
 and is used by <unk> tragic poets of the 5th century BC ; later Greeks also used <unk> <unk> , as did <unk> and Pliny , writing in Latin , in the first century AD . Pliny also gives the names <unk> [ sic ] , <unk> , alabaster , and the " very common " <unk> , " wide @-@ eye " ( from the effect of the cosmetic ) . Later Latin authors adapted the word to Latin as stibium . The Arabic word for the substance , as opposed to the cosmetic , can appear as <unk> <unk> , <unk> , <unk> , or <unk> . <unk> suggests the first form , which is the earliest , derives from <unk> , an <unk> for stimmi . 
 The use of Sb as the standard chemical symbol for antimony is due to <unk> Jakob Berzelius , who used this abbreviation of the name stibium . The medieval Latin form , from which the modern languages and late Byzantine Greek take their names for antimony , is antimonium . The origin of this is uncertain ; all suggestions have some difficulty either of form or interpretation . The popular etymology , from <unk> anti @-@ <unk> or French <unk> , still has adherents ; this would mean " monk @-@ killer " , and is explained by many early <unk> being monks , and antimony being poisonous . 
 Another popular etymology is the hypothetical Greek word <unk> <unk> , " against <unk> " , explained as " not found as metal " , or " not found <unk> " . <unk> conjectured a hypothetical Greek word <unk> <unk> , which would mean " <unk> " , and cites several examples of related Greek words ( but not that one ) which describe chemical or biological <unk> . 
 The early uses of antimonium include the translations , in <unk> – 1100 , by Constantine the African of Arabic medical <unk> . Several authorities believe antimonium is a scribal corruption of some Arabic form ; <unk> derives it from <unk> ; other possibilities include <unk> , the Arabic name of the metalloid , and a hypothetical as @-@ stimmi , derived from or parallel to the Greek . 
 
 = = Production = = 
 
 
 = = = Top producers and production volumes = = = 
 
 The British Geological Survey ( <unk> ) reported that in 2005 , China was the top producer of antimony with an approximately 84 % world share , followed at a distance by South Africa , Bolivia and <unk> . <unk> Mine in <unk> province has the largest deposits in China with an estimated deposit of 2 @.@ 1 million metric tons . 
 In 2010 , according to the US Geological Survey , China accounted for 88 @.@ 9 % of total antimony production with South Africa , Bolivia and Russia sharing the second place . 
 However , Roskill <unk> estimates for primary production show that in 2010 China held a 76 @.@ 75 % share of world supply with 120 @,@ 462 tonnes ( 90 @,@ 000 tonnes of reported and 30 @,@ <unk> tonnes of un @-@ reported production ) , followed by Russia ( 4 @.@ 14 % share , 6 @,@ 500 tonnes of production ) , <unk> ( 3 @.@ 76 % share , 5 @,@ <unk> tonnes ) , Canada ( 3 @.@ 61 % share , 5 @,@ 660 tonnes ) , <unk> ( 3 @.@ 42 % share , 5 @,@ 370 tonnes ) and Bolivia ( 3 @.@ 17 % share , 4 @,@ 980 tonnes ) . 
 Roskill estimates that secondary production globally in 2010 was 39 @,@ 540 tonnes . 
 Antimony was ranked first in a Risk List published by the British Geological Survey in the second half of 2011 . The list provides an indication of the relative risk to the supply of chemical elements or element groups required to maintain the current British economy and lifestyle . 
 Also , antimony was identified as one of 12 critical raw materials for the EU in a report published in 2011 , primarily due to the lack of supply outside China . 
 <unk> production of antimony in China fell in 2010 and is unlikely to increase in the coming years , according to the Roskill report . No significant antimony deposits in China have been developed for about ten years , and the remaining economic reserves are being rapidly depleted . 
 The world 's largest antimony producers , according to Roskill , are listed below : 
 
 = = = Reserves = = = 
 
 According to statistics from the USGS , current global reserves of antimony will be depleted in 13 years . However , the USGS expects more resources will be found . 
 
 = = = Production process = = = 
 
 The extraction of antimony from ores depends on the quality of the ore and composition of the ore . Most antimony is mined as the sulfide ; lower @-@ grade ores are concentrated by <unk> flotation , while higher @-@ grade ores are heated to 500 – 600 ° C , the temperature at which stibnite <unk> and is separated from the <unk> minerals . Antimony can be isolated from the crude antimony sulfide by a reduction with scrap iron : 
 Sb 
 2S 
 3 + 3 Fe → 2 Sb + 3 <unk> 
 The sulfide is converted to an oxide and advantage is often taken of the <unk> of antimony ( III ) oxide , which is recovered from roasting . This material is often used directly for the main applications , impurities being arsenic and sulfide . <unk> antimony from its oxide is performed by a <unk> reduction : 
 2 Sb 
 2O 
 3 + 3 C → 4 Sb + 3 CO 
 2 
 The lower @-@ grade ores are reduced in blast <unk> while the higher @-@ grade ores are reduced in <unk> <unk> . 
 
 = = Applications = = 
 
 About 60 % of antimony is consumed in flame retardants , and 20 % is used in alloys for batteries , plain bearings and solders . 
 
 = = = Flame retardants = = = 
 
 Antimony is mainly used as its trioxide in making flame @-@ <unk> compounds . It is nearly always used in combination with halogenated flame retardants , with the only exception being in <unk> @-@ containing polymers . The formation of halogenated antimony compounds is the cause for the flame <unk> effect of antimony trioxide , due to reaction of these compounds with hydrogen atoms and probably also with oxygen atoms and OH radicals , thus inhibiting fire . <unk> for these flame @-@ <unk> applications include children 's clothing , toys , aircraft and automobile seat covers . It is also used in the fiberglass <unk> industry as an <unk> to <unk> <unk> for such items as light aircraft engine covers . The resin will burn while a flame is held to it but will extinguish itself as soon as the flame is removed . 
 
 = = = <unk> = = = 
 
 Antimony forms a highly useful alloy with lead , increasing its hardness and mechanical strength . For most applications involving lead , varying amounts of antimony are used as <unk> metal . In lead – acid batteries , this addition improves the charging characteristics and reduces generation of <unk> hydrogen during charging . It is used in <unk> alloys ( such as <unk> metal ) , in bullets and lead shot , cable <unk> , type metal ( for example , for <unk> printing machines ) , <unk> ( some " lead @-@ free " solders contain 5 % Sb ) , in <unk> , and in <unk> alloys with low tin content in the manufacturing of organ pipes . 
 
 = = = Other applications = = = 
 
 Three other applications make up nearly all the rest of the consumption . One of these uses is as a <unk> and a catalyst for the production of <unk> . Another application is to serve as a fining agent to remove microscopic bubbles in glass , mostly for TV screens ; this is achieved by the interaction of antimony ions with oxygen , interfering the latter from forming bubbles . The third major application is the use as pigment . 
 Antimony is being increasingly used in the <unk> industry as a <unk> for heavily doped n @-@ type silicon <unk> in the production of diodes , infrared detectors , and Hall @-@ effect devices . In the 1950s , tiny beads of a lead @-@ antimony alloy were used to <unk> the <unk> and collectors of n @-@ p @-@ n alloy junction <unk> with antimony . <unk> antimonide is used as a material for mid @-@ infrared detectors . 
 Few biological or medical applications exist for antimony . <unk> principally containing antimony are known as <unk> and are used as <unk> . Antimony compounds are used as <unk> drugs . <unk> <unk> tartrate , or tartar emetic , was once used as an anti @-@ <unk> drug from 1919 on . It was subsequently replaced by <unk> . Antimony and its compounds are used in several <unk> preparations like <unk> or lithium antimony <unk> , which is used as a skin <unk> in <unk> . Antimony has a nourishing or conditioning effect on <unk> tissues , at least in animals . 
 Antimony @-@ based drugs , such as <unk> <unk> , are also considered the drugs of choice for treatment of <unk> in domestic animals . Unfortunately , as well as having low therapeutic <unk> , the drugs are poor at penetrating the bone marrow , where some of the <unk> amastigotes reside , and so cure of the disease – especially the visceral form – is very difficult . Elemental antimony as an antimony pill was once used as a medicine . It could be reused by others after ingestion and elimination . 
 In the heads of some safety matches , antimony ( III ) sulfide is used . Antimony @-@ 124 is used together with beryllium in neutron sources ; the gamma rays emitted by antimony @-@ 124 initiate the <unk> of beryllium . The emitted neutrons have an average energy of 24 keV . Antimony sulfides have been shown to help stabilize the friction coefficient in automotive brake pad materials . 
 Antimony also is used in the making of bullets and bullet <unk> . This element is also used in paint and glass art crafts and as <unk> in enamel . 
 
 = = Precautions = = 
 
 The effects of antimony and its compounds on human and environmental health differ widely . The massive antimony metal does not affect human and environmental health . Inhalation of antimony trioxide ( and similar poorly soluble Sb ( III ) dust particles such as antimony dust ) is considered harmful and suspected of causing cancer . However , these effects are only observed with female rats and after long @-@ term exposure to high dust concentrations . The effects are hypothesized to be attributed to inhalation of poorly soluble Sb particles leading to impaired lung clearance , lung <unk> , inflammation and ultimately <unk> formation , not to exposure to antimony ions ( <unk> , 2008 ) . Antimony <unk> are corrosive to skin . The effects of antimony are not comparable to arsenic ; this might be caused by the significant differences of uptake , metabolism and <unk> between arsenic and antimony . 
 For oral absorption , <unk> ( 1994 ) recommended values of 10 % for tartar emetic and 1 % for all other antimony compounds . <unk> absorption for metals is estimated at most 1 % ( <unk> , 2007 ) . Inhalation absorption of antimony trioxide and other poorly soluble Sb ( III ) substances ( such as antimony dust ) is estimated at 6 @.@ 8 % ( <unk> , 2008 ) , whereas a value < 1 % is derived for Sb ( V ) substances . Antimony ( V ) is not <unk> reduced to antimony ( III ) in the cell , and both species exist simultaneously . 
 Antimony is mainly excreted from the human body via urine . Antimony and its compounds do not cause acute human health effects , with the exception of antimony potassium tartrate ( " tartar emetic " ) , a <unk> that is intentionally used to treat <unk> patients . 
 <unk> skin contact with antimony dust may cause <unk> . However , it was agreed at the European Union level that the skin <unk> observed are not substance @-@ specific , but most probably due to a physical blocking of <unk> <unk> ( <unk> / PR / 09 / 09 , Helsinki , 6 July 2009 ) . Antimony dust may also be explosive when dispersed in the air ; when in a bulk solid it is not <unk> . 
 Antimony is incompatible with strong acids , halogenated acids , and <unk> ; when exposed to newly formed hydrogen it may form stibine ( <unk> ) . 
 The 8 hour time weighted average ( TWA ) is set at 0 @.@ 5 mg / m3 by the American Conference of <unk> Industrial <unk> and by the Occupational Safety and Health Administration ( <unk> ) as a legal permissible exposure limit ( <unk> ) in the workplace . The National Institute for Occupational Safety and Health ( <unk> ) has set a recommended exposure limit ( <unk> ) of 0 @.@ 5 mg / m3 as an 8 hour TWA . Antimony compounds are used as <unk> for <unk> <unk> ( <unk> ) production . Some studies report minor antimony <unk> from <unk> bottles into liquids , but levels are below drinking water guidelines . Antimony concentrations in fruit juice concentrates were somewhat higher ( up to 44 @.@ 7 µg / L of antimony ) , but <unk> do not fall under the drinking water regulations . The drinking water guidelines are : 
 World Health Organization : 20 µg / L 
 Japan : 15 µg / L 
 United States Environmental Protection Agency , Health Canada and the Ontario Ministry of Environment : 6 µg / L 
 EU and German Federal Ministry of Environment : 5 µg / L 
 The <unk> proposed by WHO is 6 µg antimony per kilogram of body weight . The <unk> ( immediately dangerous to life and health ) value for antimony is 50 mg / m3 . 
 
 