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Talc

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Formula:
Mg3(Si4O10)(OH)2
System:
Triclinic
Colour:
Colorless, white, pale ...
Lustre:
Sub-Vitreous, Resinous, Waxy, Greasy, Pearly
Hardness:
1
Name:
Allegedly named in 1546 by Georgius Agricola (Georg Bauer) from Arabic "talq", pure, probably alluding to the color of its powder.
Isostructural with:
Almost always in foliated masses ranging from white to beautiful bluish green. Usually found in metamorphic rocks with abundant carbonate minerals associated.

Visit gemdat.org for gemological information about Talc.

Classification of Talc

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
9.EC.05

9 : SILICATES (Germanates)
E : Phyllosilicates
C : Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
71.2.1.3

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
2 : Sheets of 6-membered rings with 2:1 layers
14.4.9

14 : Silicates not Containing Aluminum
4 : Silicates of Mg
mindat.org URL:
http://www.mindat.org/min-3875.html
Please feel free to link to this page.

Occurrences of Talc

Geological Setting:
Schists and steatite through hydrothermal alteration of mafic rocks. Low temperature metamorphism of siliceous dolomites.

Physical Properties of Talc

Sub-Vitreous, Resinous, Waxy, Greasy, Pearly
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Colorless, white, pale green, bright emerald-green to dark green, brown, gray
Streak:
White
Hardness (Mohs):
1
Hardness Data:
Mohs hardness reference species
Tenacity:
Sectile
Cleavage:
Perfect
on {001}
Fracture:
Fibrous, Micaceous
Comment:
Flexible but not elastic. Feels slippery or greasy to the touch.
Density:
2.58 - 2.83 g/cm3 (Measured)    2.78 g/cm3 (Calculated)

Crystallography of Talc

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 5.29Å, b = 9.173Å, c = 9.46Å
α = 90.46°, β = 98.68°, γ = 90.09°
Ratio:
a:b:c = 0.577 : 1 : 1.031
Z:
2
Morphology:
Euhedral crystals are extremely rare, usually found in platy, foliated to fine grained compact masses, sometimes has a radial appearance.
Comment:
The 1A polytype has C-1 setting.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction Data:
d-spacingIntensity
9.31 (100)
4.67 (20)
4.55 (60)
3.12 (90)
2.59 (20)
2.48 (30)
2.23 (10)
1.524 (30)
Comments:
24-1493

Optical Data of Talc

Type:
Biaxial (-)
RI values:
nα = 1.538 - 1.550 nβ = 1.589 - 1.594 nγ = 1.589 - 1.600
Birefringence:
0.05
Max Birefringence:
δ = 0.051
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v perceptible
Pleochroism:
Weak
Comments:
Only visible in dark varietites

Chemical Properties of Talc

Formula:
Mg3(Si4O10)(OH)2
Essential elements:
All elements listed in formula:
Common Impurities:
Ni,Fe,Al,Ca,Na,H2O

Relationship of Talc to other Species

Structurally related to group(s):
9.EC.05Minnesotaite(Fe,Mg)3(Si4O10)(OH)2
9.EC.05Willemseite(Ni,Mg)3(Si4O10)(OH)2
9.EC.10FerripyrophylliteFe23+(Si4O10)(OH)2
9.EC.10PyrophylliteAl2(Si4O10)(OH)2
9.EC.15BoromuscoviteKAl2(BSi3O10)(OH)2
9.EC.15CeladoniteK(Mg,Fe2+)Fe3+(Si4O10)(OH)2
9.EC.15Chernykhite(Ba,Na)(V3+,Al,Mg)2((Si,Al)4O10)(OH)2
9.EC.15Montdorite(K,Na)2(Fe2+,Mn2+,Mg)5(Si4O10)2(OH,F)4
9.EC.15MuscoviteKAl2(AlSi3O10)(OH)2
9.EC.15NanpingiteCsAl2(AlSi3O10)(OH,F)2
9.EC.15ParagoniteNaAl2(AlSi3O10)(OH)2
9.EC.15RoscoeliteK(V3+,Al)2(AlSi3O10)(OH)2
9.EC.15Tobelite(NH4,K)Al2(AlSi3O10)(OH)2
9.EC.15AluminoceladoniteK(Mg,Fe2+)Al(Si4O10)(OH)2
9.EC.15ChromphylliteK(Cr,Al)2(AlSi3O10)(OH,F)2
9.EC.15FerroaluminoceladoniteK(Fe2+,Mg)(Al,Fe3+)(Si4O10)(OH)2
9.EC.15FerroceladoniteK(Fe2+,Mg)(Fe3+,Al)(Si4O10)(OH)2
9.EC.15ChromceladoniteK(Mg,Fe2+)(Cr,Al)(Si4O10)(OH)2
9.EC.15TainioliteKLiMg2(Si4O10)F2
9.EC.15Ganterite(Ba,Na,K)(Al,Mg)2(AlSi3O10)(OH)2
9.EC.20AnniteKFe32+(AlSi3O10)(OH)2
9.EC.20EphesiteLiNaAl2(Al2Si2O10)(OH)2
9.EC.20HendricksiteK(Zn,Mg,Mn2+)3(AlSi3O10)(OH)2
9.EC.20Masutomilite(K,Rb)(Li,Mn3+,Al)3(AlSi3O10)(F,OH)2
9.EC.20NorrishiteKLiMn23+(Si4O10)O2
9.EC.20PhlogopiteKMg3(AlSi3O10)(OH,F)2
9.EC.20PolylithioniteKLi2Al(Si4O10)(F,OH)2
9.EC.20PreiswerkiteNaMg2Al(Al2Si2O10)(OH)2
9.EC.20SiderophylliteKFe22+Al(Al2Si2O10)(OH)2
9.EC.20TetraferriphlogopiteKMg3(Fe3+Si3O10)(OH,F)2
9.EC.20FluorotetraferriphlogopiteKMg3(Fe3+Si3O10)F2
9.EC.20Wonesite(Na,K)(Mg,Fe,Al)6((Al,Si)4O10)2(OH,F)4
9.EC.20EastoniteKMg2Al(Al2Si2O10)(OH)2
9.EC.20TetraferrianniteKFe32+((Fe3+,Al)Si3O10)(OH)2
9.EC.20TrilithioniteK(Li1.5Al1.5)(AlSi3O10)(F,OH)2
9.EC.20FluoranniteKFe32+(AlSi3O10)(F,OH)2
9.EC.20ShirokshiniteKNaMg2(Si4O10)F2
9.EC.20ShirozuliteK(Mn2+,Mg)3(AlSi3O10)(OH)2
9.EC.20SokolovaiteCsLi2Al(Si4O10)F2
9.EC.20AspidoliteNaMg3(AlSi3O10)(OH)2
9.EC.20FluorophlogopiteKMg3(AlSi3O10)(F,OH)2
9.EC.20UM2004-49-SiO:AlCsFHKLi(Cs,K)(Al,Li)2.6((Si,Al)4O10)(F,OH)2
9.EC.20Suhailite(NH4)Fe32+(AlSi3O10)(OH)2
9.EC.20YangzhumingiteKMg2.5(Si4O10)F2
9.EC.20OrloviteKLi2Ti(Si4O10)OF
9.EC.20OxyphlogopiteK(Mg,Ti,Fe)3[(Si,Al)4O10](O,F)2
9.EC.25Brammallite(Na,H3O)(Al,Mg,Fe)2((Si,Al)4O10)(OH)2
9.EC.30MargariteCaAl2(Al2Si2O10)(OH)2
9.EC.35Anandite(Ba,K)(Fe2+,Mg)3((Si,Al,Fe)4O10)(S,OH)2
9.EC.35BityiteLiCaAl2(AlBeSi2O10)(OH)2
9.EC.35ClintoniteCa(Mg,Al)3(Al3SiO10)(OH)2
9.EC.35Kinoshitalite(Ba,K)(Mg,Mn2+,Al)3(Al2Si2O10)(OH)2
9.EC.35Ferrokinoshitalite(Ba,K)(Fe2+,Mg)3(Al2Si2O10)(OH,F)2
9.EC.35Oxykinoshitalite(Ba,K)(Mg,Ti,Fe3+,Fe2+)3((Si,Al)4O10)(O,OH,F)2
9.EC.35FluorokinoshitaliteBaMg3(Al2Si2O10)F2
9.EC.40Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
9.EC.40Kurumsakite(Zn,Ni,Cu)8Al8V25+Si5O35 · 27H2O (?)
9.EC.40Montmorillonite(Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 · nH2O
9.EC.40NontroniteNa0.3Fe2((Si,Al)4O10)(OH)2 · nH2O
9.EC.40VolkonskoiteCa0.3(Cr,Mg,Fe)2((Si,Al)4O10)(OH)2 · 4H2O
9.EC.40Yakhontovite(Ca,Na)0.5(Cu,Fe,Mg)2(Si4O10)(OH)2 · 3H2O
9.EC.45HectoriteNa0.3(Mg,Li)3(Si4O10)(F,OH)2
9.EC.45SaponiteCa0.25(Mg,Fe)3((Si,Al)4O10)(OH)2 · nH2O
9.EC.45SauconiteNa0.3Zn3((Si,Al)4O10)(OH)2 · 4H2O
9.EC.45SpadaiteMgSiO2(OH)2 · H2O (?)
9.EC.45Stevensite(Ca,Na)xMg3-x(Si4O10)(OH)2
9.EC.45SwineforditeLi(Al,Li,Mg)4((Si,Al)4O10)2(OH,F)4 · nH2O
9.EC.45ZincsiliteZn3(Si4O10)(OH)2 · 4H2O
9.EC.45FerrosaponiteCa0.3(Fe2+,Mg,Fe3+)3((Si,Al)4O10)(OH)2 · 4H2O
9.EC.50Vermiculite(Mg,Fe,Al)3((Al,Si)4O10)(OH)2 · 4H2O
9.EC.55Baileychlore(Zn,Fe,Al,Mg)6((Si,Al)4O10)(OH)8
9.EC.55Chamosite(Fe2+,Mg)5Al(AlSi3O10)(OH)8
9.EC.55Clinochlore(Mg,Fe2+)5Al(AlSi3O10)(OH)8
9.EC.55Cookeite(Al2Li)Al2(AlSi3O10)(OH)8
9.EC.55FranklinfurnaceiteCa2Fe3+Mn32+Mn3+(Zn2Si2O10)(OH)8
9.EC.55Gonyerite(Mn2+,Mg)5Fe3+(Fe3+Si3O10)(OH)8
9.EC.55Nimite(Ni,Mg,Al)6((Si,Al)4O10)(OH)8
9.EC.55Orthochamosite(Fe2+,Mg,Fe3+)5Al(AlSi3O10)(OH,O)8
9.EC.55PennantiteMn52+Al(AlSi3O10)(OH)8
9.EC.55Sudoite(Mg,Fe2+)2Al3(AlSi3O10)(OH)8
9.EC.55DonbassiteAl4.33(AlSi3O10)(OH)8
9.EC.55GlagoleviteNa(Mg,Al)6(AlSi3O10)(OH,O)8
9.EC.55BorocookeiteLi1+3xAl4-x(BSi3O10)(OH)8
9.EC.60AliettiteCa0.2Mg6((Si,Al)8O20)(OH)4 · 4H2O
9.EC.60Corrensite(Mg,Fe)9((Si,Al)8O20)(OH)10 · nH2O
9.EC.60DozyiteMg7Al2(Al2Si4O15)(OH)12
9.EC.60HydrobiotiteK(Mg,Fe2+)6((Si,Al)8O20)(OH)4 · nH2O
9.EC.60Karpinskite(Ni,Mg)2Si2O5(OH)2 (?)
9.EC.60KulkeiteMg8Al(AlSi7O20)(OH)10
9.EC.60LunijianlaiteLi0.7Al6.2(AlSi7O20)(OH,O)10
9.EC.60Rectorite(Na,Ca)Al4((Si,Al)8O20)(OH)4 · 2H2O
9.EC.60Saliotite(Li,Na)Al3(AlSi3O10)(OH)5
9.EC.60TosuditeNa0.5(Al,Mg)6((Si,Al)8O18)(OH)12 · 5H2O
9.EC.60BrinrobertsiteNa0.3Al4(Si4O10)2(OH)4 · 3.5 H2O
9.EC.65Macaulayite(Fe,Al)24Si4O43(OH)2
9.EC.70BurckhardtitePb2(Fe3+Te6+)[AlSi3O8]O6
9.EC.75Ferrisurite(Pb,Ca)2.4Fe23+(Si4O10)(CO3)1.7(OH)3 · nH2O
9.EC.75Surite(Pb,Ca)3(Al,Fe2+,Mg)2((Si,Al)4O10)(CO3)2(OH)2
9.EC.75Niksergievite(Ba,Ca)2Al3(AlSi3O10)(CO3)(OH)6 · nH2O
9.EC.80KegelitePb8Al4(Si8O20)(SO4)2(CO3)4(OH)8
14.4.1ForsteriteMg2SiO4
14.4.2EnstatiteMgSiO3
14.4.3ClinoenstatiteMgSiO3
14.4.4ChrysotileMg3(Si2O5)(OH)4
14.4.5Clinochrysotile
14.4.6Orthochrysotile
14.4.7Parachrysotile
14.4.8LizarditeMg3(Si2O5)(OH)4
14.4.10SpadaiteMgSiO2(OH)2 · H2O (?)
14.4.11SepioliteMg4(Si6O15)(OH)2 · 6H2O
14.4.12LoughliniteNa2Mg3Si6O16 · 8H2O
14.4.13EifeliteKNa3Mg4Si12O30
14.4.14Stevensite(Ca,Na)xMg3-x(Si4O10)(OH)2
14.4.15AntigoriteMg3(Si2O5)(OH)4
14.4.16 Magnesio-anthophyllite

Other Names for Talc

Name in Other Languages:
Arabic:تلك
Basque:Talko
Bulgarian:Талк
Catalan:Talc
Croatian:Talk
Czech:Mastek
Danish:Fedtsten
Dutch:Talk
Esperanto:Talko
Finnish:Talkki
Galician:Talco
Hebrew:טלק
Hungarian:Zsírkő
Italian:Talco
Japanese:滑石
Latvian:Talks
Lithuanian:Talkas
Norwegian (Bokmål):Talk
Polish:Talk
Portuguese:Talco
Romanian:Talc
Russian:Тальк
Serbian (Cyrillic Script):Талк
Simplified Chinese:滑石
Slovenian:Lojevec
Swedish:Talk
Turkish:Talk
Ukrainian:Тальк

Other Information

Not usually fluorescent
Thermal Behaviour:
Stable to about 900 degrees Celsius
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Filler in paints, rubber. In cosmetics and as a lubricating dusting powder.

References for Talc

Reference List:
Rayner, J.H., & G. Brown, The crystal structure of talc: Clays and Clay Minerals: 21: 103-114.

Avgustinik, A.I. and Vigderganz, V.S. (1948) Properties of talc during heating. Ogneupory: 13: 218-227.

Krönert, W., Schwiete, H.E., and Suchow, A. (1964a) Das thermische Verhalten von Speckstein und die Stabilität der Magnesiummetasilikat-Modifikationen. Ziegelindustrie: 17: 364-369.

Krönert, W., Schwiete, H.E., and Suchow, A. (1964b) Über das thermische Verhalten von Speckstein und die Stabilität der MgSiO3-Modifikationen. Naturwissenschaften: 51: 85-86.

Bošković, S.B., Gašić, M.Č., Nikolić, V.S., and Ristić, M.M. (1968) The structural changes of talc during heating. Proceedings of the British Ceramic Society: 10: 1-12.

Perdikatsis B., Burzlaff H. (1981), Zeitschrift für Kristallographie: 156: 177.

Wesolowski, M. (1984) Thermal decomposition of talc: a review. Thermochimica Acta: 78: 395-421.

Pawley, A.R., Redfern, S.A.T., and Wood, B.J. (1995) Thermal expansivities and compressibilities of hydrous phases in the system MgO-SiO2-H2O: talc, phase A, and 10-Å Phase. Contributions to Mineralogy and Petrology: 122: 301-307.

Ferrage, E., Martin, F., Petit, S., Pejo-Soucaille, S., Micoud,P., Fourty, G., Ferret, J., Salvi, S., de Parseval, P., and Fortune, J.P. (2003) Evaluation of talc morphology using FTIR and H/D substitution. Clay Minerals: 38: 141-150.

Petit, S., Martin, F., Wieqiora, A., de Parseval, P., and Decarreau, A. (2004) Crystal-chemistry of talc: A near infrared (NIR) spectroscopy study. American Mineralogist: 89: 319-326.

Zhang, M., Hui, Q., Lou, X.-J., Redfern, A.T., Salje, E.K.H., and Tarantino, S.C. (2006) Dehydroxylation, proton migration, and structural changes in heated talc: An infrared spectroscopic study: American Mineralogist: 91: 816-825.

Internet Links for Talc

Specimens:
The following Talc specimens are currently listed for sale on minfind.com.

Localities for Talc

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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