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

Images:

Click Here for Larger Pyrophyllite Image

Pyrophyllite Rutile

Comments: Rutile on fine-grained pyrophyllite.
Location: Graves Mt. Georgia, USA. Scale: 4.5 x 5 cm.
© Fabre Minerals

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

$Help on X Ray Diffraction:$ 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 :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Pyrophyllite Specimen Label here :

Pyrophyllite

Al2Si4O10(OH)2
Dana No: 71.02.01.01 Strunz No: 09.EC.10
Locality:

Notes: