Pyrophyllite Mineral Data

General Pyrophyllite Information

Chemical Formula: Al2Si4O10(OH)2 Composition: Molecular Weight = 360.31 gm    Aluminum  14.98 %  Al   28.30 % Al₂O₃    Silicon   31.18 %  Si   66.70 % SiO₂    Hydrogen   0.56 %  H     5.00 % H₂O    Oxygen    53.28 %  O             ______        ______              100.00 %      100.00 % = TOTAL OXIDE Empirical Formula: Al₂Si₄O₁₀(OH)₂ Environment: Somewhat uncommon, found both in hydrothermal veins and in bedded deposits in schistose metamorphic rocks. IMA Status: Valid Species (Pre-IMA) 1829 Locality: Tres Cerritos, California, USA; Pyschminsk and Beresovsk, Ural Mountains, Russia. Link to MinDat.org Location Data. Name Origin: From the Greek for fie and leaf, in allusion to its tendency to exfoliate into fan shapes when heated. Name Pronunciation: Pyrophyllite + Pronunciation  

Pyrophyllite Image

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Pyrophyllite Crystallography

Axial Ratios: a:b:c =0.5761:1:1.0439 Cell Dimensions: a = 5.161, b = 8.957, c = 9.351, Z = 2; alpha = 91.03°, beta = 100.37°, gamma = 89.75° V = 425.14 Den(Calc)= 2.81 Crystal System: Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1 X Ray Diffraction: By Intensity(I/I_o): 4.42(1), 9.2(0.9), 3.07(0.85), Crystal Structure:

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Wardle R , Brindley G W , American Mineralogist , 57 (1972) p.732-750, The crystal structures of pyrophyllite, 1Tc, and of its dehydroxylate View Additional jPOWD Structure files for Pyrophyllite [1] [2]

 

Physical Properties of Pyrophyllite

Cleavage: {001} Perfect Color: Brown green, Brownish yellow, Greenish, Gray green, Gray white. Density: 2.8 - 2.9, Average = 2.84 Diaphaneity: Translucent to opaque Fracture: Flexible - Flexible fragments. Habit: Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite). Hardness: 1.5-2 - Talc-Gypsum Luminescence: Fluorescent, Long UV=butter yellow. Luster: Pearly Streak: white  

Optical Properties of Pyrophyllite

Gladstone-Dale: CI meas= 0.055 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.042 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2053,KPDmeas= 0.2025,KC= 0.2143
Ncalc = 1.6 - 1.62 Optical Data: Biaxial (-), a=1.534-1.556, b=1.586-1.589, g=1.596-1.601, bire=0.0450-0.0620, 2V(Calc)=46-60, 2V(Meas)=53-62. Dispersion none. Pleochroism (x): colorless. Pleochroism (y): colorless.  

Calculated Properties of Pyrophyllite

Electron Density: Bulk Density (Electron Density)=2.81 gm/cc
note: Specific Gravity of Pyrophyllite =2.81 gm/cc.
Fermion Index: Fermion Index = 0.01
Boson Index = 0.99 Photoelectric: PE_Pyrophyllite = 1.65 barns/electron
U=PE_Pyrophyllite x rElectron Density= 4.62 barns/cc.
Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Pyrophyllite is Not Radioactive  

Pyrophyllite Classification

Dana Class: 71.02.01.01 (71)Phyllosilicate Sheets of Six-Membered Rings   (71.02)with 2:1 Layers   (71.02.01)Pyrophyllite-talc group  

71.02.01.01 Pyrophyllite Al2Si4O10(OH)2 P1 1

 

71.02.01.02 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m

 

71.02.01.03 Talc Mg3Si4O10(OH)2 C 2/c 2/m

 

71.02.01.04 Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m

 

71.02.01.05 Minnesotaite (Fe,Mg)3Si4O10(OH)2 C1 1

 

71.02.01.06 Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O)[x=0.35,n=3.54] pseudo 2/m 2/m

Strunz Class: 09.EC.10 09 - SILICATES (Germanates)   09.E - Phyllosilicates   09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets  

09.EC.10 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m

 

09.EC.10 Pyrophyllite Al2Si4O10(OH)2 P1 1

 

Other Pyrophyllite Information

See Also: Links to other databases for Pyrophyllite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - GeoScienceWorld
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - HyperPhysics
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - Scandinavian mineral gallery
16 - WWW-MINCRYST
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Ask about Pyrophyllite here :
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Mineral Discussion Forum from Fabre Minerals - also available in Español

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