Pyrophyllite Mineral Data

Pyrophyllite Mineral Data +

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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

IMA Status:

Valid Species (Pre-IMA) 1829

Locality:

Pyschminsk and Beresovsk, Ural Mountains, Russia. Link to MinDat.org Location Data.

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

Diaphaniety:

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.

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

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.

Pleochroism (z):

colorless.

Calculated Properties of Pyrophyllite

Electron Density:

r_electron=2.81 gm/cc
note: r_Pyrophyllite=2.81 gm/cc.

Fermion Index

Fermion Index = 0.01481
Boson Index = 0.98519

Photoelectric:

PE_Pyrophyllite= 1.65 barns/electron
U=PE_Pyrophyllite x r_electron= 4.62 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Pyrophyllite is Not Radioactive

Pyrophyllite Classification

Dana Class:

71.2.1.1 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.2)with 2:1 Layers

(71.2.1)Pyrophyllite-talc group

71.2.1.1 Pyrophyllite Al2Si4O10(OH)2 P1 1

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

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

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

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

71.2.1.6 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:

VIII/H.09-10 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like layered silicates with [Si4O10]4- and related groups

VIII/H.09 - Talc series

VIII/H.09-10 Pyrophyllite Al2Si4O10(OH)2 P1 1

VIII/H.09-20 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m

VIII/H.09-30 Macaulayite (Fe,Al)24Si4O43(OH)2 C? Mono

VIII/H.09-40 Talc Mg3Si4O10(OH)2 C 2/c 2/m

VIII/H.09-50 Minnesotaite (Fe,Mg)3Si4O10(OH)2 C1 1

VIII/H.09-60 Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m

VIII/H.09-65 Pimelite Ni3Si4O10(OH)2·4(H2O) Unk. Hex

VIII/H.09-70 Kegelite Pb8Al4Si8O20(SO4)2(CO3)4(OH)8 A2/m,A2,Am Mono

Other Pyrophyllite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Pyrophyllite

Al2Si4O10(OH)2
Dana No: 71.2.1.1 Strunz No: VIII/H.09-10
Locality:

Notes: