The Mineral Talc: Uses, Properties, Photos - Geology.com

Talc: Talc is a phyllosilicate mineral that cleaves into thin sheets. These sheets are held together only by van der Waals bonds, which allows them to easily ... Geology.comNewsRocksMineralsGemstonesVolcanoesMoreTopicsUSMapsWorldMapStore HomepageArticlesDiamondsEarthquakesGemstonesGeneralGeologyGeologicHazardsGoldLandslidesMetalsMeteorites MineralsNewsOilandGasPlateTectonicsRocksSatelliteImagesStoreU.S.MapsVolcanoesWorldMap Advertising Categories DiamondsEarthquakesFossilsGemstonesGeneralGeologyGeologicHazardsGeologyDictionaryGeologyNewsGeology.comStoreGoldLandslidesMetalsMeteoritesMineralsOilandGasPlateTectonicsRocksRockTumblersSatelliteImagesTeacherResourcesU.S.A.MapsVolcanoesWorldMapWorldRecords MapCollections AfricaMapsAntarcticaMapArcticMapAsiaMapsAustraliaMapCanadaMapsCaribbeanMapsCentralAmericaMapsEuropeMapsNorthAmericaMapsSouthAmericaMapsUnitedStatesMapsWorldMaps Advertising Home»Minerals»Talc Talc:TheSoftestMineral WhatisTalc?  HowDoesitForm?  HowisTalcUsed? Articleby:HobartM.King,PhD,RPG Usesoftalc:Talcisusedinawidevarietyofproductsthatweseeeveryday.Itisanimportantingredientinrubber,afillerandwhitenerinpaint,afillerandbrighteningagentinhigh-qualitypapers,andaprimaryingredientinmanytypesofcosmetics.ImagescopyrightiStockphotoand(clockwise)MorePixels,MarkWragg,Franz-W.Franzelin,andHighImpactPhotography. Talc:AMineralinYourDailyLife Mostpeoplearefamiliarwiththemineralknownas"talc".Itcanbecrushedintoawhitepowderthatiswidelyknownas"talcumpowder."Thispowderhastheabilitytoabsorbmoisture,absorboils,absorbodor,serveasalubricant,andproduceanastringenteffectwithhumanskin.Thesepropertieshavemadetalcumpowderanimportantingredientinmanybabypowders,footpowders,firstaidpowders,andavarietyofcosmetics. Aformoftalcknownas"soapstone"isalsowidelyknown.Thissoftrockiseasilycarvedandhasbeenusedtomakeornamentalandpracticalobjectsforthousandsofyears.Ithasbeenusedtomakesculptures,bowls,countertops,sinks,hearths,pipebowls,andmanyotherobjects. ADVERTISEMENT Althoughtalcumpowderandsoapstonearetwoofthemorevisibleusesoftalc,theyaccountforaverysmallfractionoftalcconsumption.Itshiddenusesarefarmorecommon.Talc'suniquepropertiesmakeitanimportantingredientformakingceramics,paint,paper,roofingmaterials,plastics,rubber,insecticides,andmanyotherproducts. Talc:Talcisaphyllosilicatemineralthatcleavesintothinsheets.ThesesheetsareheldtogetheronlybyvanderWaalsbonds,whichallowsthemtoeasilyslippastoneanother.Thischaracteristicisresponsiblefortalc'sextremesoftness,itsgreasytosoapyfeel,anditsvalueasahigh-temperaturelubricant. WhatisTalc? TalcisahydrousmagnesiumsilicatemineralwithachemicalcompositionofMg3Si4O10(OH)2.Althoughthecompositionoftalcusuallystaysclosetothisgeneralizedformula,somesubstitutionoccurs.SmallamountsofAlorTicansubstituteforSi;smallamountsofFe,Mn,andAlcansubstituteforMg;and,verysmallamountsofCacansubstituteforMg. WhenlargeamountsofFesubstituteforMg,themineralisknownasminnesotaite.WhenlargeamountsofAlsubstituteforMg,themineralisknownaspyrophyllite. Talcisusuallygreen,white,gray,brown,orcolorless.Itisatranslucentmineralwithapearlyluster.Itisthesoftestknownmineralandisassignedahardnessof1ontheMohsHardnessScale. Talcisamonoclinicmineralwithasheetstructuresimilartothemicas.Talchasperfectcleavagethatfollowsplanesbetweentheweaklybondedsheets.ThesesheetsareheldtogetheronlybyvanderWaalsbonds,whichallowsthemtoslippastoneanothereasily.Thischaracteristicisresponsiblefortalc'sextremesoftness,itsgreasy,soapyfeel,anditsvalueasahigh-temperaturelubricant. ADVERTISEMENT WhereisTalcProduced? 2018MineProductionofTalc Country ThousandMetricTons UnitedStates620 Brazil850 China1,800 Finland350 France450 India900 Japan370 SouthKorea610 OtherCountries1,500 ThevaluesaboveareestimatesofmineproductionsinthousandsofmetrictonsfromtheUSGSMineralCommoditySummaries. IntheUnitedStates,talcconsumptionhasslowlydeclinedsince1995.Smalleramountsofthemineralareusedintheceramicsindustrybecauseofachangeinfiringtechnology.Inthepaintindustry,ashiftfromoil-basedpaintstolatexpaintshasdecreasedtheuseoftalc.Inthecosmeticsindustry,manymanufacturershavereplacedtalcwithcornstarchpowderinmanyproductsinresponsetohealthconcernsandlitigation.However,theplasticsindustryisusingmoretalc,asthemineralbecomesamoreimportantingredientinautomotiveplastics.Theamountoftalcusedinrubberproductionhasalsoincreasedslightly. MinesintheUnitedStateshavetheabilitytoproducemostgradesoftalctomaketheUnitedStatesself-sufficient.However,somegradesoftalccanbeimportedfromothercountriesatlowercosts.Thisreducesemploymentandrevenueindomesticminingandprocessingcompanies. Theleadingtalc-producingcountriesin2018wereChina,India,Brazil,theUnitedStates,SouthKorea,France,Japan,andFinland.Numerousothercountriesareminorproducersoftalc. TheUnitedStates,talcisfoundintheeasternAppalachianandPiedmontregionsfromNewEnglandtoAlabama.ImportantdepositsarelocatedinCalifornia,Montana,Nevada,TexasandWashington. Soapstone:Arockknownas"soapstone"isamassivevarietyoftalcwithvaryingamountsofothermineralssuchasmicas,chlorite,amphiboles,andpyroxenes.Itisasoftrockthatiseasytowork,whichhascausedittobeusedinawidevarietyofdimensionstoneandsculptureapplications.Itisusedforcountertops,electricalpanels,hearthstones,figurines,statuary,andmanyotherprojects. ADVERTISEMENT HowDoesTalcForm? Talcisamineralthatismostoftenfoundinthemetamorphicrocksofconvergentplateboundaries.Itformsfromatleasttwoprocesses.MostlargetalcdepositsintheUnitedStatesformedwhenheatedwaters,carryingdissolvedmagnesiumandsilica,reactedwithdolomiticmarbles.Asecondprocessoftalcformationoccurredwhenheatandchemicallyactivefluidsalteredrockssuchasduniteandserpentiniteintotalc. MostofthetalcdepositsintheUnitedStatesareinmetamorphicrocksontheeasternsideoftheAppalachianMountainsandinrocksmetamorphosedinconvergentterranesofWashington,Idaho, Montana,California,Nevada,andNewMexico.DepositsoftalcarealsofoundinTexas. Foliatedtalc:Talcisametamorphicmineralthatfrequentlyexhibitsdistinctfoliation. TalcMiningandProcessing MosttalcintheUnitedStatesisproducedfromanopen-pitminewheretherockisdrilled,blasted,andpartiallycrushedintheminingoperation.Thehighestgradeoresareproducedbyselective miningandsortingoperations. Greatcareistakenduringtheminingprocesstoavoidcontaminatingthetalcwithotherrockmaterials.Theseothermaterialscanhaveanadverseeffectonthecoloroftheproduct.Contaminationcanintroducehardparticlesthatcauseproblemsinapplicationswheretalcisbeingusedbecauseofitssoftnessorlubricatingproperties. Partiallycrushedrockistakenfromtheminetoamill,whereitisfurtherreducedinparticlesize.Impuritiesaresometimesremovedbyfrothflotationormechanicalprocessing.Themillsusuallyproducecrushedorfinelygroundtalcthatmeetscustomerrequirementsforparticlesize,brightness,composition,andotherproperties. UsesofTalc:Talcisusedasafiller,coating,pigment,dustingagent,andextenderinplastics,ceramics,paint,paper,cosmetics,roofing,rubberandmanyotherproducts.DatafromtheUnitedStatesGeologicalSurvey. Talc:Foliatedtalcthathasablackcolorinmassiveformbutcleavesintothin,flexible,inelasticandcolorlesssheets. PhysicalPropertiesofTalc ChemicalClassification Silicate Color Green,white,gray,brown,colorless Streak Whitetopalegreen Luster Pearly Diaphaneity Translucent Cleavage Perfect MohsHardness 1 SpecificGravity 2.7to2.8 DiagnosticProperties Feel,color,softness,cleavage ChemicalComposition Mg3Si4O10(OH)2 CrystalSystem Monoclinic Uses Usedasafillerandanti-stickcoatinginplastics,ceramics,paint,paper,roofing,rubber,cosmetics Thebestwaytolearnaboutmineralsistostudywithacollectionofsmallspecimensthatyoucanhandle,examine,andobservetheirproperties.InexpensivemineralcollectionsareavailableintheGeology.comStore.ImagecopyrightiStockphoto/AnnaUsova. TalcInformation [1]TalcandPyrophyllite:RobertL.Virta,U.S.GeologicalSurvey,MineralCommoditySummaries,January2012. [2]TalcandPyrophyllite:RobertL.Virta,U.S.GeologicalSurvey,2010MineralsYearbook,November2011. [3]U.S.Talc--BabyPowderandMuchMore:U.S.GeologicalSurvey,FactSheetFS-065-00,September2000. [4]TalcresourcesoftheconterminousUnitedStates:RobertC.Greene,UnitedStatesGeologicalSurvey,Open-FileReportOF95-586,1995. [5]TalcinCosmetics:UnitedStatesFoodandDrugAdministration,websitearticle,lastaccessedAugust2016. UsesofTalc Mostpeopleuseproductsmadefromtalceveryday;however,theydon'trealizethattalcisintheproduct-orthespecialrolethatitplays. TalcinPlastics In2011,about26%ofthetalcconsumedintheUnitedStateswasusedinthemanufacturingofplastics.Itismainlyusedasafiller.Theplatyshapeoftalcparticlescanincrease thestiffnessofproductssuchaspolypropylene,vinyl,polyethylene,nylon,andpolyester.Itcanalsoincreasetheheatresistanceoftheseproductsandreduceshrinkage.Where theplasticisextrudedinthemanufacturingprocess,talc'sverylowhardnessproduceslessabrasiononequipmentthanhardermineralfillers. TalcinCeramics IntheUnitedStatesin2011,about17%ofthetalcconsumedwasusedinthemanufacturingofceramicsproductssuchasbathroomfixtures,ceramictile,pottery,anddinnerware.Whenusedasafillerinceramics,talccanimprovethefiringcharacteristicsofthegreenwareandthestrengthofthefinishedproduct. TalcinPaint Mostpaintsaresuspensionsofmineralparticlesinaliquid.Theliquidportionofthepaintfacilitatesapplication,butaftertheliquidevaporates,themineralparticlesremainonthewall.Talcisusedasanextenderandfillerinpaints.Theplatyshapeoftalcparticlesimprovesthesuspensionofsolidsinthecanandhelpstheliquidpaintadheretoawallwithoutsagging. Powderedtalcisaverybrightwhitecolor.Thismakestalcanexcellentfillerinpaintbecauseitsimultaneouslyservestowhitenandbrightenthepaint.Talc'slowhardnessisvaluedbecauseit causeslessabrasiondamageonspraynozzlesandotherequipmentwhenpaintisapplied.In2011,about16%ofthetalcconsumedintheUnitedStateswasusedtomakepaint. TalcinPaper Mostpapersaremadefromapulpoforganicfibers.Thispulpismadefromwood,rags,andotherorganicmaterials.Finelygroundmineralmatterisaddedtothepulptoserveasafiller.Whenthepulpisrolledintothinsheets,themineralmatterfillsspacesbetweenthepulpfibers,resultinginapaperwithamuchsmootherwritingsurface.Talcasamineralfillercanimprovetheopacity,brightness,andwhitenessofthepaper.Talccanalsoimprovethepaper'sabilitytoabsorbink.In2011,thepaperindustryconsumedabout16%ofthetalcusedintheUnitedStates. TalcinCosmeticsandAntiperspirants Finelygroundtalcisusedasthepowderbaseofmanycosmeticproducts.Thetinyplateletsofatalcpowderreadilyadheretotheskinbutcanbewashedoffeasily.Talc'ssoftnessallowsittobeappliedandremovedwithoutcausingskinabrasion. Talcalsohastheabilitytoabsorboilsandperspirationproducedbyhumanskin.Theabilityoftalctoabsorbmoisture,absorbodor,adheretotheskin,serveasalubricant,andproducean astringenteffectincontactwithhumanskinmakeitanimportantingredientinmanyantiperspirants.In2011,about7%ofthetalcconsumedintheUnitedStateswasusedtomakecosmeticsandantiperspirant. Talcandasbestosoccurnaturallyandmayoccurincloseproximityinsomemetamorphicrocks.Studiespublishedinthe1960sand1970sidentifiedhealthconcernsabouttheuseoftalcthatcontainsasbestosinsomecosmeticproducts. AccordingtotheFDA,"Thesestudieshavenotconclusivelydemonstratedsuchalink,orifsuchalinkexisted,whatriskfactorsmightbeinvolved."Toaddresstheseconcerns,talcminingsitesarenowcarefullyselected,andoresarecarefullyprocessedtoavoidthepresenceofasbestosintalcdestinedforuseinthecosmeticsindustry. TalcinRoofingMaterials Talcisaddedtotheasphalticmaterialsusedtomakeroofingmaterialstoimprovetheirweatherresistance.Itisalsodustedontothesurfaceofrollroofingandshinglestopreventsticking.In2011,about6%ofthetalcconsumedintheUnitedStateswasusedtomanufactureroofingmaterials. DimensionStone Arockknownas"soapstone"isamassivevarietyoftalcwithvaryingamountsofothermineralssuchasmicas,chlorite,amphiboles,andpyroxenes.Itisasoftrockthatiseasytowork,whichhascausedittobeusedinawidevarietyofdimensionstoneandsculptureapplications.Itisusedforcountertops,electricalpanels, hearthstones,figurines,statuary,andmanyotherprojects. OtherUsesofTalc Groundtalcisusedasalubricantinapplicationswherehightemperaturesareinvolved.Itisabletosurviveattemperatureswhereoil-basedlubricantswouldbedestroyed. Talcpowderisusedasacarrierforinsecticidesandfungicides.Itcaneasilybeblownthroughanozzleandreadilystickstotheleavesandstemsofplants.Itssoftnessreduceswearonapplicationequipment. 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