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Pyrophyllite

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Formula:
Al2Si4O10(OH)2
Colour:
White, gray, pale blue, pale green, pale yellow, brownish green
Lustre:
Pearly, Dull
Hardness:
1 - 2
Specific Gravity:
2.65 - 2.9
Crystal System:
Triclinic
Name:
From the Greek for "fire" (πῦρ, pyr) and "leaf" (φύλλον, phyllos) for the way it exfoliates when heated.
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Classification of PyrophylliteHide

Approved, 'Grandfathered' (first described prior to 1959)
9.EC.10

9 : SILICATES (Germanates)
E : Phyllosilicates
C : Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
71.2.1.1

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
2 : Sheets of 6-membered rings with 2:1 layers
15.5

15 : Silicates of Aluminum

Physical Properties of PyrophylliteHide

Pearly, Dull
Transparency:
Translucent, Opaque
Colour:
White, gray, pale blue, pale green, pale yellow, brownish green
Hardness:
1 - 2 on Mohs scale
Tenacity:
Flexible
Cleavage:
Perfect
on {001}
Comment:
inelastic
Density:
2.65 - 2.9 g/cm3 (Measured)    2.81 g/cm3 (Calculated)

Optical Data of PyrophylliteHide

Type:
Biaxial (-)
RI values:
nα = 1.534 - 1.556 nβ = 1.586 - 1.589 nγ = 1.596 - 1.601
2V:
Measured: 53° to 62°, Calculated: 46° to 60°
Max Birefringence:
δ = 0.062
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v weak

Chemical Properties of PyrophylliteHide

Formula:
Al2Si4O10(OH)2

Crystallography of PyrophylliteHide

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Cell Parameters:
a = 5.16 Å, b = 8.966(3) Å, c = 9.347(6) Å
α = 91.18°, β = 100.46°, γ = 89.64°
Ratio:
a:b:c = 0.576 : 1 : 1.042
Unit Cell V:
425.16 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Lamellar crystals, spherulitic aggregates, granular, massive.
Comment:
Space group C-1.

X-Ray Powder DiffractionHide

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Type Occurrence of PyrophylliteHide

Synonyms of PyrophylliteHide

Other Language Names for PyrophylliteHide

Varieties of PyrophylliteHide

Cattle Egg StoneA dense variety of pyrophyllite with black interior and yellow exterior, which is used for carving. The colours are due to microscopic inclusions of iron oxides in different states of weathering. The yellow parts of the material also contain minor diaspor...
Chrome-PyrophylliteA Cr-bearing variety of pyrophyllite.
Originally reported from Mitterberg District, Dienten, Salzburg, Austria.
GelpyrophylliteThe gel form of Pyrophyllite

Relationship of Pyrophyllite to other SpeciesHide

Other Members of this group:
FerripyrophylliteFe3+Si2O5(OH)Mon.
MinnesotaiteFe2+3Si4O10(OH)2Tric. 1 : P1
TalcMg3Si4O10(OH)2Tric. 1 : P1
WillemseiteNi3Si4O10(OH)2Mon.

Common AssociatesHide

Associated Minerals Based on Photo Data:
Rutile30 photos of Pyrophyllite associated with Rutile on mindat.org.
Quartz16 photos of Pyrophyllite associated with Quartz on mindat.org.
Kyanite11 photos of Pyrophyllite associated with Kyanite on mindat.org.
Pyrite6 photos of Pyrophyllite associated with Pyrite on mindat.org.
Yttrocrasite-(Y)4 photos of Pyrophyllite associated with Yttrocrasite-(Y) on mindat.org.
Chloritoid4 photos of Pyrophyllite associated with Chloritoid on mindat.org.
Svanbergite4 photos of Pyrophyllite associated with Svanbergite on mindat.org.
Hematite4 photos of Pyrophyllite associated with Hematite on mindat.org.
Lazulite4 photos of Pyrophyllite associated with Lazulite on mindat.org.
Gormanite3 photos of Pyrophyllite associated with Gormanite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.EC.05MinnesotaiteFe2+3Si4O10(OH)2Tric. 1 : P1
9.EC.05TalcMg3Si4O10(OH)2Tric. 1 : P1
9.EC.05WillemseiteNi3Si4O10(OH)2Mon.
9.EC.10FerripyrophylliteFe3+Si2O5(OH)Mon.
9.EC.15BoromuscoviteKAl2(BSi3O10)(OH)2Mon.
9.EC.15CeladoniteK(Mg,Fe2+)Fe3+(Si4O10)(OH)2Mon. 2/m : B2/m
9.EC.15Chernykhite(Ba,Na)(V3+,Al,Mg)2((Si,Al)4O10)(OH)2Mon.
9.EC.15Montdorite(K,Na)2(Fe2+,Mn2+,Mg)5(Si4O10)2(OH,F)4
9.EC.15MuscoviteKAl2(AlSi3O10)(OH)2Mon. 2/m : B2/b
9.EC.15NanpingiteCsAl2(AlSi3O10)(OH,F)2Mon.
9.EC.15ParagoniteNaAl2(AlSi3O10)(OH)2Mon.
9.EC.15RoscoeliteK(V3+,Al)2(AlSi3O10)(OH)2Mon. 2/m : B2/b
9.EC.15Tobelite(NH4,K)Al2(AlSi3O10)(OH)2Mon.
9.EC.15AluminoceladoniteK(Mg,Fe2+)Al(Si4O10)(OH)2Mon.
9.EC.15ChromphylliteK(Cr,Al)2(AlSi3O10)(OH,F)2Mon. 2/m : B2/b
9.EC.15FerroaluminoceladoniteK(Fe2+,Mg)(Al,Fe3+)(Si4O10)(OH)2Mon. 2/m : B2/m
9.EC.15FerroceladoniteK(Fe2+,Mg)(Fe3+,Al)(Si4O10)(OH)2Mon. 2/m : B2/m
9.EC.15ChromceladoniteK(Mg,Fe2+)(Cr,Al)(Si4O10)(OH)2Mon.
9.EC.15TainioliteKLiMg2(Si4O10)F2Mon.
9.EC.15Ganterite(Ba,Na,K)(Al,Mg)2(AlSi3O10)(OH)2Mon.
9.EC.20AnniteKFe2+3(AlSi3O10)(OH)2Mon. 2/m : B2/m
9.EC.20EphesiteLiNaAl2(Al2Si2O10)(OH)2Tric.
9.EC.20HendricksiteK(Zn,Mg,Mn2+)3(AlSi3O10)(OH)2Mon. 2/m : B2/m
9.EC.20Masutomilite(K,Rb)(Li,Mn3+,Al)3(AlSi3O10)(F,OH)2Mon.
9.EC.20NorrishiteKLiMn3+2(Si4O10)O2Mon. 2/m : B2/m
9.EC.20PhlogopiteKMg3(AlSi3O10)(OH)2Mon. 2/m : B2/m
9.EC.20PolylithioniteKLi2Al(Si4O10)(F,OH)2Mon. 2/m : B2/b
9.EC.20PreiswerkiteNaMg2Al(Al2Si2O10)(OH)2Mon.
9.EC.20SiderophylliteKFe2+2Al(Al2Si2O10)(OH)2Mon.
9.EC.20TetraferriphlogopiteKMg3(Fe3+Si3O10)(OH,F)2
9.EC.20FluorotetraferriphlogopiteKMg3(Fe3+Si3O10)F2Mon. 2/m : B2/m
9.EC.20Wonesite(Na,K)(Mg,Fe,Al)6((Al,Si)4O10)2(OH,F)4Mon. 2/m : B2/m
9.EC.20EastoniteKMg2Al(Al2Si2O10)(OH)2Mon.
9.EC.20TetraferrianniteKFe2+3((Fe3+,Al)Si3O10)(OH)2Mon.
9.EC.20TrilithioniteK(Li1.5Al1.5)(AlSi3O10)(F,OH)2Mon. 2/m : B2/b
9.EC.20FluoranniteKFe2+3(AlSi3O10)(F,OH)2Mon.
9.EC.20ShirokshiniteKNaMg2(Si4O10)F2Mon. 2/m : B2/m
9.EC.20ShirozuliteK(Mn2+,Mg)3(AlSi3O10)(OH)2Mon. 2/m : B2/m
9.EC.20SokolovaiteCsLi2Al(Si4O10)F2Mon.
9.EC.20AspidoliteNaMg3(AlSi3O10)(OH)2Mon. 2/m : B2/m
9.EC.20FluorophlogopiteKMg3(AlSi3O10)(F,OH)2Mon. 2/m : B2/m
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)2Mon. 2/m : B2/m
9.EC.20YangzhumingiteKMg2.5(Si4O10)F2Mon. 2/m : B2/m
9.EC.20OrloviteKLi2Ti(Si4O10)OFMon. 2 : B2
9.EC.20OxyphlogopiteK(Mg,Ti,Fe)3[(Si,Al)4O10](O,F)2Mon. 2/m : B2/m
9.EC.25Brammallite(Na,H3O)(Al,Mg,Fe)2((Si,Al)4O10)(OH)2Mon.
9.EC.30MargariteCaAl2(Al2Si2O10)(OH)2Mon.
9.EC.35Anandite(Ba,K)(Fe2+,Mg)3((Si,Al,Fe)4O10)(S,OH)2Mon. 2/m : B2/b
9.EC.35BityiteLiCaAl2(AlBeSi2O10)(OH)2Mon. 2/m : B2/b
9.EC.35ClintoniteCa(Mg,Al)3(Al3SiO10)(OH)2Mon. 2/m : B2/m
9.EC.35Kinoshitalite(Ba,K)(Mg,Mn2+,Al)3(Al2Si2O10)(OH)2Mon.
9.EC.35Ferrokinoshitalite(Ba,K)(Fe2+,Mg)3(Al2Si2O10)(OH,F)2Mon.
9.EC.35Oxykinoshitalite(Ba,K)(Mg,Ti,Fe3+,Fe2+)3((Si,Al)4O10)(O,OH,F)2Mon. 2/m : B2/m
9.EC.35FluorokinoshitaliteBaMg3(Al2Si2O10)F2Mon. 2/m : B2/m
9.EC.40Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2OMon.
9.EC.40Kurumsakite(Zn,Ni,Cu)8Al8V5+2Si5O35 · 27H2O (?)
9.EC.40Montmorillonite(Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 · nH2OMon. 2/m : B2/m
9.EC.40NontroniteNa0.3Fe2((Si,Al)4O10)(OH)2 · nH2OMon.
9.EC.40VolkonskoiteCa0.3(Cr,Mg,Fe)2((Si,Al)4O10)(OH)2 · 4H2OMon.
9.EC.40Yakhontovite(Ca,Na)0.5(Cu,Fe,Mg)2(Si4O10)(OH)2 · 3H2OMon.
9.EC.45HectoriteNa0.3(Mg,Li)3(Si4O10)(F,OH)2Mon.
9.EC.45SaponiteCa0.25(Mg,Fe)3((Si,Al)4O10)(OH)2 · nH2OMon.
9.EC.45SauconiteNa0.3Zn3((Si,Al)4O10)(OH)2 · 4H2OMon.
9.EC.45SpadaiteMgSiO2(OH)2 · H2O (?)
9.EC.45Stevensite(Ca,Na)xMg3-x(Si4O10)(OH)2Mon.
9.EC.45SwineforditeLi(Al,Li,Mg)4((Si,Al)4O10)2(OH,F)4 · nH2OMon.
9.EC.45ZincsiliteZn3(Si4O10)(OH)2 · 4H2OMon.
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 · 8H2OMon. 2/m
9.EC.55Baileychlore(Zn,Fe2+,Al,Mg)6(Si,Al)4O10(OH)8Tric.
9.EC.55Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8Mon.
9.EC.55ClinochloreMg5Al(AlSi3O10)(OH)8Mon. 2/m : B2/m
9.EC.55Cookeite(Al2Li)Al2(AlSi3O10)(OH)8Mon. 2/m
9.EC.55FranklinfurnaceiteCa2Fe3+Mn2+3Mn3+(Zn2Si2O10)(OH)8Mon. 2 : B2
9.EC.55Gonyerite(Mn2+,Mg)5Fe3+(Fe3+Si3O10)(OH)8
9.EC.55Nimite(Ni,Mg,Al)6((Si,Al)4O10)(OH)8Mon.
9.EC.55Orthochamosite(Fe2+,Mg,Fe3+)5Al(AlSi3O10)(OH,O)8
9.EC.55PennantiteMn2+5Al(AlSi3O10)(OH)8Tric.
9.EC.55SudoiteMg2Al3(Si3Al)O10)(OH)8Mon.
9.EC.55DonbassiteAl4.33(AlSi3O10)(OH)8Mon. 2 : B2
9.EC.55GlagoleviteNa(Mg,Al)6(AlSi3O10)(OH,O)8Tric. 1 : P1
9.EC.55BorocookeiteLi1+3xAl4-x(BSi3O10)(OH)8
9.EC.60AliettiteCa0.2Mg6((Si,Al)8O20)(OH)4 · 4H2OMon.
9.EC.60Corrensite(Mg,Fe)9((Si,Al)8O20)(OH)10 · nH2OOrth.
9.EC.60DozyiteMg7Al2(Al2Si4O15)(OH)12Mon.
9.EC.60HydrobiotiteK(Mg,Fe2+)6((Si,Al)8O20)(OH)4 · nH2OMon.
9.EC.60Karpinskite(Ni,Mg)2Si2O5(OH)2 (?)
9.EC.60KulkeiteMg8Al(AlSi7O20)(OH)10Mon.
9.EC.60LunijianlaiteLi0.7Al6.2(AlSi7O20)(OH,O)10Mon.
9.EC.60Rectorite(Na,Ca)Al4((Si,Al)8O20)(OH)4 · 2H2OMon.
9.EC.60Saliotite(Li,Na)Al3(AlSi3O10)(OH)5Mon.
9.EC.60TosuditeNa0.5(Al,Mg)6((Si,Al)8O18)(OH)12 · 5H2OMon. 2 : B2
9.EC.60BrinrobertsiteNa0.3Al4(Si4O10)2(OH)4 · 3.5 H2OMon.
9.EC.65Macaulayite(Fe,Al)24Si4O43(OH)2Mon.
9.EC.70BurckhardtitePb2(Fe3+Te6+)[AlSi3O8]O6Trig. 3m (3 2/m) : P3 1m
9.EC.75Ferrisurite(Pb,Ca)2.4Fe3+2(Si4O10)(CO3)1.7(OH)3 · nH2OMon.
9.EC.75Surite(Pb,Ca)3(Al,Fe2+,Mg)2((Si,Al)4O10)(CO3)2(OH)2Mon.
9.EC.75Niksergievite(Ba,Ca)2Al3(AlSi3O10)(CO3)(OH)6 · nH2OMon.
9.EC.80KegelitePb8Al4(Si8O20)(SO4)2(CO3)4(OH)8Mon.

Related Minerals - Dana Grouping (8th Ed.)Hide

71.2.1.2FerripyrophylliteFe3+Si2O5(OH)Mon.
71.2.1.3TalcMg3Si4O10(OH)2Tric. 1 : P1
71.2.1.4WillemseiteNi3Si4O10(OH)2Mon.
71.2.1.5MinnesotaiteFe2+3Si4O10(OH)2Tric. 1 : P1

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

15.1AndalusiteAl2(SiO4)OOrth. mmm (2/m 2/m 2/m) : Pnnm
15.2KyaniteAl2(SiO4)OTric. 1 : P1
15.3SillimaniteAl2(SiO4)OOrth. mmm (2/m 2/m 2/m)
15.4MulliteAl4+2xSi2-2xO10-xOrth. mmm (2/m 2/m 2/m) : Pbam
15.6DickiteAl2(Si2O5)(OH)4Mon. m : Bb
15.7NacriteAl2(Si2O5)(OH)4Mon. m : Bb
15.8KaoliniteAl2(Si2O5)(OH)4Tric. 1 : P1
15.9MetahalloysiteAl2(Si2O5)(OH)4
15.10HalloysiteAl2(Si2O5)(OH)4Mon. m : Bb
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2OAmor.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Pyrophyllite in petrologyHide

Common component of (items highlighted in red)

References for PyrophylliteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Hermann, R. (1829) Zerlegung des Pyrophyllits, eines neuen Minerals. Annalen der Physik und Chemie: 15: 592-592.
Gruner, J.W. (1934) The crystal structure of Pyrophyllite: Zeitschrift für Kristallographie: 88: 412-419.
Kerrick, D.M. (1968) Experiments on the upper stability limit of Pyrophyllite at 1.8 kilobars and 3.9 kilobars water pressure: American Journal of Science: 266: 204-214.
Gorniy Zhournal: 9: 452-460.
Brindley, G.W., Wardle, R. (1970) Monoclinic and triclinic forms of pyrophyllite and pyrophyllite anhydride. American Mineralogist: 55: 1259-1272.
Lee, J.H., Guggenheim, S. (1981) Single crystal X-ray refinement of pyrophyllite-1 Tc. American Mineralogist: 66: 350-357.
MacKenzie, K.J.D., Brown, I.W.M., Meinhold, R.H., Bowden, M.E.J. (1985) Thermal reactions of pyrophyllite studied by high-resolution solid-state 27Al and 29Si nuclear magnetic resonance spectroscopy. Journal of the American Ceramic Society: 68: 266-272.
Cassedanne, J.P. (1989) Pyrophyllite from Ibitiara, Brazil. Mineralogical Record: 20(6): 465-467.
Fitzgerald, J.J., Hamza, A.I., Dc, S.F., Bronnimann, C.E. (1996) Solid-state 27Al and 29Si NMR and 1H CRAMPS studies of the 2:1 phyllosilicate pyrophyllite. Journal of Physical Chemistry: 100: 17351-17360.
Wang, L., Zhang, M., Redfern, S.A.T., Zhang, Z.Y. (2002) Dehydroxylation and transformation of the 2:1 phyllosilicate pyrophyllite at elevated temperatures: An infrared spectroscopic study. Clays and Clay Minerals: 50: 272-283.
Wang, L., Zhang, M., Redfern, S.A.T. (2003) Infrared study of CO2 incorporation into pyrophyllite [Al2Si4O10(OH)2] during dehydroxylation. Clays and Clay Minerals: 51: 439-444.
Sainz-Díaz, C.I., Escamilla-Roa, E., Hernández-Laguna, A. (2004) Pyrophyllite dehydroxylation process by First Principle calculations. American Mineralogist: 89: 1092-1100.
Kogure, T., Jige, M., Kameda, J., Yamagishi, A., Miyawaki, R., Kitagawa, R. (2006) Stacking structures in pyrophyllite revealed by high-resolution transmission electron microscopy (HRTEM). American Mineralogist: 91: 1293-1299.
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 PyrophylliteHide

Localities for PyrophylliteHide

This 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.

Locality ListShow

Mineral and/or Locality  
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