 = 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 Vannoccio Biringuccio and described in 1540 , although in primitive cultures its powder has been used to cure eye ailments , 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 Xikuangshan Mine in Hunan . 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 alloying material for lead and tin and for lead antimony plates in lead – acid batteries . Alloying lead and tin with antimony improves the properties of the alloys which are used in solders , bullets and plain bearings . Antimony compounds are prominent additives for chlorine and bromine @-@ containing fire retardants found in many commercial and domestic products . An emerging application is the use of antimony in microelectronics . 
 
 = = Characteristics = = 
 
 
 = = = Properties = = = 
 
 Antimony is in the nitrogen group ( group 15 ) and has an electronegativity of 2 @.@ 05 . As expected from periodic trends , it is more electronegative than tin or bismuth , and less electronegative than tellurium or arsenic . Antimony is stable in air at room temperature , but reacts with oxygen if heated , to form antimony trioxide , Sb2O3 . 
 Antimony is a silvery , lustrous gray metalloid that has a Mohs scale hardness of 3 . Thus pure antimony is too soft to make hard objects ; coins made of antimony were issued in China 's Guizhou province in 1931 , but because of their rapid wear , their minting was discontinued . Antimony is resistant to attack by acids . 
 Four allotropes of antimony are known : a stable metallic form and three metastable forms ( explosive , black and yellow ) . Elemental antimony is a brittle , silver @-@ white shiny metalloid . When slowly cooled , molten antimony crystallizes in a trigonal cell , isomorphic with the gray allotrope of arsenic . A rare explosive form of antimony can be formed from the electrolysis of antimony trichloride . When scratched with a sharp implement , an exothermic reaction occurs and white fumes are given off as metallic antimony is formed ; when rubbed with a pestle 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 ( SbH3 ) 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 R3m No. 166 ) in which layers consist of fused ruffled six @-@ membered rings . The nearest and next @-@ nearest neighbors form an irregular octahedral 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 brittleness of antimony . 
 
 = = = Isotopes = = = 
 
 Antimony has two stable isotopes : 121Sb with a natural abundance of 57 @.@ 36 % and 123Sb with a natural abundance of 42 @.@ 64 % . It also has 35 radioisotopes , of which the longest @-@ lived is 125Sb with a half @-@ life of 2 @.@ 75 years . In addition , 29 metastable states have been characterized . The most stable of these is 120m1Sb with a half @-@ life of 5 @.@ 76 days . Isotopes that are lighter than the stable 123Sb 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 thallium 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 natively ( 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 . 
 
 = = = Oxides and hydroxides = = = 
 
 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 polymerizes upon condensing . Antimony pentoxide ( 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 amphoteric , do not form well @-@ defined oxoacids and react with acids to form antimony salts . 
 Antimonous acid Sb ( OH ) 
 3 is unknown , but the conjugate base sodium antimonite ( [ Na 
 3SbO 
 3 ] 
 4 ) forms upon fusing sodium oxide and Sb 
 4O 
 6 . Transition metal antimonites are also known . Antimonic acid exists only as the hydrate HSb ( OH ) 
 6 , forming salts containing the antimonate anion Sb ( OH ) − 
 6 . Dehydrating metal salts containing this anion yields mixed oxides . 
 Many antimony ores are sulfides , including stibnite ( Sb 
 2S 
 3 ) , pyrargyrite ( Ag 
 3SbS 
 3 ) , zinkenite , jamesonite , and boulangerite . Antimony pentasulfide is non @-@ stoichiometric and features antimony in the + 3 oxidation state and S @-@ S bonds . Several thioantimonides are known , such as [ Sb 
 6S 
 10 ] 2 − and [ Sb 
 8S 
 13 ] 2 − . 
 
 = = = Halides = = = 
 
 Antimony forms two series of halides : SbX 
 3 and SbX 
 5 . The trihalides SbF 
 3 , SbCl 
 3 , SbBr 
 3 , and SbI 
 3 are all molecular compounds having trigonal pyramidal molecular geometry . 
 The trifluoride 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 SbF2 − 
 5 . Molten SbF 
 3 is a weak electrical conductor . The trichloride SbCl 
 3 is prepared by dissolving Sb 
 2S 
 3 in hydrochloric acid : 
 Sb 
 2S 
 3 + 6 HCl → 2 SbCl 
 3 + 3 H 
 2S 
 The pentahalides SbF 
 5 and SbCl 
 5 have trigonal bipyramidal molecular geometry in the gas phase , but in the liquid phase , SbF 
 5 is polymeric , whereas SbCl 
 5 is monomeric . SbF 
 5 is a powerful Lewis acid used to make the superacid fluoroantimonic acid ( " H2SbF7 " ) . 
 Oxyhalides are more common for antimony than arsenic and phosphorus . Antimony trioxide dissolves in concentrated acid to form oxoantimonyl compounds such as SbOCl and ( SbO ) 
 2SO 
 4 . 
 
 = = = Antimonides , hydrides , and organoantimony compounds = = = 
 
 Compounds in this class generally are described as derivatives of Sb3 − . Antimony forms antimonides with metals , such as indium antimonide ( InSb ) and silver antimonide ( Ag 
 3Sb ) . The alkali metal and zinc antimonides , such as Na3Sb and Zn3Sb2 , are more reactive . Treating these antimonides with acid produces the unstable gas stibine , SbH 
 3 : 
 Sb3 − + 3 H + → SbH 
 3 
 Stibine can also be produced by treating Sb3 + salts with hydride reagents such as sodium borohydride.Stibine decomposes spontaneously at room temperature . Because stibine has a positive heat of formation , it is thermodynamically unstable and thus antimony does not react with hydrogen directly . 
 Organoantimony compounds are typically prepared by alkylation of antimony halides with Grignard reagents . A large variety of compounds are known with both Sb ( III ) and Sb ( V ) centers , including mixed chloro @-@ organic derivatives , anions , and cations . Examples include Sb ( C6H5 ) 3 ( triphenylstibine ) , Sb2 ( C6H5 ) 4 ( with an Sb @-@ Sb bond ) , and cyclic [ Sb ( C6H5 ) ] n . Pentacoordinated organoantimony 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 Telloh , Chaldea ( part of present @-@ day Iraq ) , and a copper object plated with antimony dating between 2500 BC and 2200 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 . " 
 Moorey was unconvinced the artifact was indeed a vase , mentioning that Selimkhanov , after his analysis of the Tello object ( published in 1975 ) , " attempted to relate the metal to Transcaucasian natural antimony " ( i.e. native metal ) and that " the antimony objects from Transcaucasia 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 friable , has been suspected to be native metallic antimony . 
 The Roman naturalist Pedanius Dioscorides 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 pirotechnia of 1540 by Vannoccio Biringuccio ; this predates the more famous 1556 book by Agricola , De re metallica . In this context Agricola has been often incorrectly credited with the discovery of metallic antimony . The book Currus Triumphalis Antimonii ( The Triumphal 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 Basilius Valentinus , 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 Libavius 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 phlogiston 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 Swab in 1783 ; the type @-@ sample was collected from the Sala Silver Mine in the Bergslagen mining district of Sala , Västmanland , Sweden . 
 
 = = = Etymology = = = 
 
 The ancient words for antimony mostly have , as their chief meaning , kohl , the sulfide of antimony . 
 The Egyptians called antimony mśdmt ; in hieroglyphs , the vowels are uncertain , but there is an Arabic tradition that the word is ميسديميت mesdemet . The Greek word , στίμμι stimmi , is probably a loan word from Arabic or from Egyptian stm 
 and is used by Attic tragic poets of the 5th century BC ; later Greeks also used στἰβι stibi , as did Celsus and Pliny , writing in Latin , in the first century AD . Pliny also gives the names stimi [ sic ] , larbaris , alabaster , and the " very common " platyophthalmos , " 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 إثمد ithmid , athmoud , othmod , or uthmod . Littré suggests the first form , which is the earliest , derives from stimmida , an accusative for stimmi . 
 The use of Sb as the standard chemical symbol for antimony is due to Jöns 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 ἀντίμοναχός anti @-@ monachos or French antimoine , still has adherents ; this would mean " monk @-@ killer " , and is explained by many early alchemists being monks , and antimony being poisonous . 
 Another popular etymology is the hypothetical Greek word ἀντίμόνος antimonos , " against aloneness " , explained as " not found as metal " , or " not found unalloyed " . Lippmann conjectured a hypothetical Greek word ανθήμόνιον anthemonion , which would mean " floret " , and cites several examples of related Greek words ( but not that one ) which describe chemical or biological efflorescence . 
 The early uses of antimonium include the translations , in 1050 – 1100 , by Constantine the African of Arabic medical treatises . Several authorities believe antimonium is a scribal corruption of some Arabic form ; Meyerhof derives it from ithmid ; other possibilities include athimar , 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 ( BGS ) 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 Tajikistan . Xikuangshan Mine in Hunan 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 Consulting 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 @,@ 464 tonnes of un @-@ reported production ) , followed by Russia ( 4 @.@ 14 % share , 6 @,@ 500 tonnes of production ) , Myanmar ( 3 @.@ 76 % share , 5 @,@ 897 tonnes ) , Canada ( 3 @.@ 61 % share , 5 @,@ 660 tonnes ) , Tajikistan ( 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 . 
 Reported 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 froth flotation , while higher @-@ grade ores are heated to 500 – 600 ° C , the temperature at which stibnite melts and is separated from the gangue minerals . Antimony can be isolated from the crude antimony sulfide by a reduction with scrap iron : 
 Sb 
 2S 
 3 + 3 Fe → 2 Sb + 3 FeS 
 The sulfide is converted to an oxide and advantage is often taken of the volatility of antimony ( III ) oxide , which is recovered from roasting . This material is often used directly for the main applications , impurities being arsenic and sulfide . Isolating antimony from its oxide is performed by a carbothermal reduction : 
 2 Sb 
 2O 
 3 + 3 C → 4 Sb + 3 CO 
 2 
 The lower @-@ grade ores are reduced in blast furnaces while the higher @-@ grade ores are reduced in reverberatory furnaces . 
 
 = = 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 @-@ proofing compounds . It is nearly always used in combination with halogenated flame retardants , with the only exception being in halogen @-@ containing polymers . The formation of halogenated antimony compounds is the cause for the flame retarding 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 . Markets for these flame @-@ retardant applications include children 's clothing , toys , aircraft and automobile seat covers . It is also used in the fiberglass composites industry as an additive to polyester resins 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 . 
 
 = = = Alloys = = = 
 
 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 alloying metal . In lead – acid batteries , this addition improves the charging characteristics and reduces generation of unwanted hydrogen during charging . It is used in antifriction alloys ( such as Babbitt metal ) , in bullets and lead shot , cable sheathing , type metal ( for example , for linotype printing machines ) , solder ( some " lead @-@ free " solders contain 5 % Sb ) , in pewter , and in hardening 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 stabilizer and a catalyst for the production of polyethyleneterephthalate . 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 semiconductor industry as a dopant for heavily doped n @-@ type silicon wafers in the production of diodes , infrared detectors , and Hall @-@ effect devices . In the 1950s , tiny beads of a lead @-@ antimony alloy were used to dope the emitters and collectors of n @-@ p @-@ n alloy junction transistors with antimony . Indium antimonide is used as a material for mid @-@ infrared detectors . 
 Few biological or medical applications exist for antimony . Treatments principally containing antimony are known as antimonials and are used as emetics . Antimony compounds are used as antiprotozoan drugs . Potassium antimonyl tartrate , or tartar emetic , was once used as an anti @-@ schistosomal drug from 1919 on . It was subsequently replaced by praziquantel . Antimony and its compounds are used in several veterinary preparations like anthiomaline or lithium antimony thiomalate , which is used as a skin conditioner in ruminants . Antimony has a nourishing or conditioning effect on keratinized tissues , at least in animals . 
 Antimony @-@ based drugs , such as meglumine antimoniate , are also considered the drugs of choice for treatment of leishmaniasis in domestic animals . Unfortunately , as well as having low therapeutic indices , the drugs are poor at penetrating the bone marrow , where some of the Leishmania 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 photodisintegration 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 tracers . This element is also used in paint and glass art crafts and as opacifier 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 overload , inflammation and ultimately tumour formation , not to exposure to antimony ions ( OECD , 2008 ) . Antimony chlorides 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 excretion between arsenic and antimony . 
 For oral absorption , ICRP ( 1994 ) recommended values of 10 % for tartar emetic and 1 % for all other antimony compounds . Dermal absorption for metals is estimated at most 1 % ( HERAG , 2007 ) . Inhalation absorption of antimony trioxide and other poorly soluble Sb ( III ) substances ( such as antimony dust ) is estimated at 6 @.@ 8 % ( OECD , 2008 ) , whereas a value < 1 % is derived for Sb ( V ) substances . Antimony ( V ) is not quantitatively 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 prodrug that is intentionally used to treat leishmaniasis patients . 
 Prolonged skin contact with antimony dust may cause dermatitis . However , it was agreed at the European Union level that the skin rashes observed are not substance @-@ specific , but most probably due to a physical blocking of sweat ducts ( ECHA / 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 combustible . 
 Antimony is incompatible with strong acids , halogenated acids , and oxidizers ; when exposed to newly formed hydrogen it may form stibine ( SbH3 ) . 
 The 8 hour time weighted average ( TWA ) is set at 0 @.@ 5 mg / m3 by the American Conference of Governmental Industrial Hygienists and by the Occupational Safety and Health Administration ( OSHA ) as a legal permissible exposure limit ( PEL ) in the workplace . The National Institute for Occupational Safety and Health ( NIOSH ) has set a recommended exposure limit ( REL ) of 0 @.@ 5 mg / m3 as an 8 hour TWA . Antimony compounds are used as catalysts for polyethylene terephthalate ( PET ) production . Some studies report minor antimony leaching from PET 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 juices 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 TDI proposed by WHO is 6 µg antimony per kilogram of body weight . The IDLH ( immediately dangerous to life and health ) value for antimony is 50 mg / m3 . 
 
 