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Talc

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Formula:
Mg3Si4O10(OH)2
Colour:
Colorless, white, pale green, bright emerald-green to dark green, brown, gray
Lustre:
Sub-Vitreous, Resinous, Waxy, Greasy, Pearly
Hardness:
1
Specific Gravity:
2.58 - 2.83
Crystal System:
Triclinic
Name:
Allegedly named in 1546 by Georgius Agricola (Georg Bauer) from Arabic "talq", pure, probably alluding to the color of its powder.
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

Approved, 'Grandfathered' (first described prior to 1959)
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

Physical Properties of Talc

Sub-Vitreous, Resinous, Waxy, Greasy, Pearly
Transparency:
Transparent, Translucent
Colour:
Colorless, white, pale green, bright emerald-green to dark green, brown, gray
Streak:
White
Hardness:
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)

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 varieties

Chemical Properties of Talc

Formula:
Mg3Si4O10(OH)2
Common Impurities:
Ni,Fe,Al,Ca,Na,H2O

Crystallography of Talc

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 5.29 Å, b = 9.173 Å, c = 9.46 Å
α = 90.46°, β = 98.68°, γ = 90.09°
Ratio:
a:b:c = 0.577 : 1 : 1.031
Unit Cell V:
453.77 ų (Calculated from Unit Cell)
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.
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

Synonyms of Talc

Other Language Names for Talc

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

Varieties of Talc

Beaconite

A fibrous variety of Talc resembling asbestos.
Originally reported from Champion Mine (Beacon Mine), Champion, Marquette iron range, Marquette Co., Michigan, USA.

Chromian Talc

A chromian variety of talc

Polyphant Stone

A greyish-green potstone flecked with whiteand brown. Used since Norman times as an ornamental stone in churches.

Pseudolite

Octahedral talc pseudomorphs after spinel.

Steatite

A massive variety of Talc with a greasy feeling, often used for ornamental carvings.

Zincian Talc

Zn-bearing variety from the "Mixed Series" formation, Nežilovo, Macedonia. Associates, i.a., with ferricoronadite.

Relationship of Talc to other Species

Other Members of this group:
FerripyrophylliteFe3+Si2O5(OH)
MinnesotaiteFe2+3Si4O10(OH)2
PyrophylliteAl2Si4O10(OH)2
WillemseiteNi3Si4O10(OH)2

Common Associates

Associated Minerals Based on Photo Data:
Quartz39 photos of Talc associated with Quartz on mindat.org.
Actinolite38 photos of Talc associated with Actinolite on mindat.org.
Calcite33 photos of Talc associated with Calcite on mindat.org.
Magnesite21 photos of Talc associated with Magnesite on mindat.org.
Pyrite19 photos of Talc associated with Pyrite on mindat.org.
Kyanite15 photos of Talc associated with Kyanite on mindat.org.
Magnetite15 photos of Talc associated with Magnetite on mindat.org.
Tremolite13 photos of Talc associated with Tremolite on mindat.org.
Dolomite13 photos of Talc associated with Dolomite on mindat.org.
Hematite11 photos of Talc associated with Hematite on mindat.org.

Related Minerals - Nickel-Strunz Grouping

9.EC.05MinnesotaiteFe2+3Si4O10(OH)2
9.EC.05WillemseiteNi3Si4O10(OH)2
9.EC.10FerripyrophylliteFe3+Si2O5(OH)
9.EC.10PyrophylliteAl2Si4O10(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.20AnniteKFe2+3(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.20NorrishiteKLiMn3+2(Si4O10)O2
9.EC.20PhlogopiteKMg3(AlSi3O10)(OH)2
9.EC.20PolylithioniteKLi2Al(Si4O10)(F,OH)2
9.EC.20PreiswerkiteNaMg2Al(Al2Si2O10)(OH)2
9.EC.20SiderophylliteKFe2+2Al(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.20TetraferrianniteKFe2+3((Fe3+,Al)Si3O10)(OH)2
9.EC.20TrilithioniteK(Li1.5Al1.5)(AlSi3O10)(F,OH)2
9.EC.20FluoranniteKFe2+3(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)Fe2+3(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)8Al8V5+2Si5O35 · 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.50VermiculiteMg0.7(Mg,Fe,Al)6(Si,Al)8O20(OH)4 · 8H2O
9.EC.55Baileychlore(Zn,Fe2+,Al,Mg)6(Si,Al)4O10(OH)8
9.EC.55Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
9.EC.55ClinochloreMg5Al(AlSi3O10)(OH)8
9.EC.55Cookeite(Al2Li)Al2(AlSi3O10)(OH)8
9.EC.55FranklinfurnaceiteCa2Fe3+Mn2+3Mn3+(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.55PennantiteMn2+5Al(AlSi3O10)(OH)8
9.EC.55SudoiteMg2Al3(Si3Al)O10)(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)2.4Fe3+2(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

Related Minerals - Hey's Chemical Index of Minerals Grouping

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☐{Mg2}{Mg5}(Si8O22)(OH)2

Related Minerals - Dana Grouping (8th Ed.)

71.2.1.1PyrophylliteAl2Si4O10(OH)2
71.2.1.2FerripyrophylliteFe3+Si2O5(OH)
71.2.1.4WillemseiteNi3Si4O10(OH)2
71.2.1.5MinnesotaiteFe2+3Si4O10(OH)2

Fluorescence of Talc

Not usually fluorescent

Other Information

Thermal Behaviour:
Stable to about 900 degrees Celsius
Health Risks:
So-called talcum powders may have small amounts of amphibole contamination.
Industrial Uses:
Filler in paints, rubber. In cosmetics and as a lubricating dusting powder.

Talc in petrology

An essential component of (items highlighted in red)
Accessory component of (items highlighted in red)

References for Talc

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Agricola, G. (1546) Talk. in De Ortu & Causis Subterraneorum Lib. V, Froben (Basileae) 480-480.
Bras-de-Fer, L. (1778) (84) Terre (Élément). In Explication Morale du Jeu de Cartes; Anecdote Curieuse et Interessante, (Bruxelles): 99-100.
Avgustinik, A.I., Vigderganz, V.S. (1948) Properties of talc during heating. Ogneupory: 13: 218-227.
Krönert, W., Schwiete, H.E., Suchow, A. (1964) Das thermische Verhalten von Speckstein und die Stabilität der Magnesiummetasilikat-Modifikationen. Ziegelindustrie: 17: 364-369.
Krönert, W., Schwiete, H.E., Suchow, A. (1964) 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., Ristić, M.M. (1968) The structural changes of talc during heating. Proceedings of the British Ceramic Society: 10: 1-12.
Rayner, J.H., Brown, G. (1973) The crystal structure of talc. Clays and Clay Minerals: 21: 103-114.
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., 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., 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., 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., Tarantino, S.C. (2006) Dehydroxylation, proton migration, and structural changes in heated talc: An infrared spectroscopic study: American Mineralogist: 91: 816-825.
Drits, V.A., Guggenheim, S., Zviagina, B.B., Kogure, T. (2012) Structures of the 2:1 layers of pyrophyllite and talc. Clays and Clay Minerals: 60: 574-587.

Internet Links for Talc

mindat.org URL:
https://www.mindat.org/min-3875.html
Please feel free to link to this page.
Specimens:
The following Talc specimens are currently listed for sale on minfind.com.

Localities for Talc

Mineral and/or Locality  
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