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Pyrophyllite

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Formula:
Al2(Si4O10)(OH)2
System:
Monoclinic
Colour:
White, gray, pale blue, ...
Hardness:
1 - 2
Name:
From the Greek for "fire" (πῦρ, pyr) and "leaf" (φύλλον, phyllos) for the way it exfoliates when heated.

Classification of Pyrophyllite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
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Type Occurrence of Pyrophyllite

Occurrences of Pyrophyllite

Geological Setting:
Hydrothermal veins and in bedded deposits in schistose rocks.

Physical Properties of Pyrophyllite

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

Crystallography of Pyrophyllite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 5.16Å, 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 Volume:
V 425.25 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Lamellar crystals, spherulitic aggregates, granular, massive
X-Ray Powder Diffraction:
Image Loading

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

Optical Data of Pyrophyllite

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 Pyrophyllite

Formula:
Al2(Si4O10)(OH)2
Essential elements:
All elements listed in formula:

Relationship of Pyrophyllite to other Species

Structurally related to group(s):
9.EC.05Minnesotaite(Fe,Mg)3(Si4O10)(OH)2
9.EC.05TalcMg3(Si4O10)(OH)2
9.EC.05Willemseite(Ni,Mg)3(Si4O10)(OH)2
9.EC.10FerripyrophylliteFe23+(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)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
15.1AndalusiteAl2(SiO4)O
15.2KyaniteAl2(SiO4)O
15.3SillimaniteAl2(SiO4)O
15.4MulliteAl4+2xSi2-2xO10-x
15.6DickiteAl2(Si2O5)(OH)4
15.7NacriteAl2(Si2O5)(OH)4
15.8KaoliniteAl2(Si2O5)(OH)4
15.9Metahalloysite
15.10HalloysiteAl2(Si2O5)(OH)4
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O

Other Names for Pyrophyllite

Name in Other Languages:

Other Information

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

References for Pyrophyllite

Reference List:
Gruner, J.W. (1934), The crystal structure of Pyrophyllite: Zeits. Krist.: 88: 412.

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.

American Mineralogist (1970) 55: 1259-1272.

American Mineralogist (1981): 66: 350-357.

MacKenzie, K.J.D., Brown, I.W.M., Meinhold, R.H., and 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.

Mineralogical Record (1989): 20: 465.

Fitzgerald, J.J., Hamza, A.I., Dc, S.F., and 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., and 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., and 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., and Hernández-Laguna, A. (2004) Pyrophyllite dehydroxylation process by First Principle calculations. American Mineralogist: 89: 1092-1100.

Internet Links for Pyrophyllite

Localities for Pyrophyllite

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.
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