Talc Mineral Data + 
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- 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
- 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
General Talc Information |
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 Chemical Formula: |
Mg3Si4O10(OH)2 | ||
| Composition: |
Molecular Weight = 379.27 gm | ||
| Magnesium 19.23 % Mg 31.88 % MgO | |||
| Silicon 29.62 % Si 63.37 % SiO2 | |||
| Hydrogen 0.53 % H 4.75 % H2O | |||
| Oxygen 50.62 % O | |||
| ______ ______ | |||
| 100.00 % 100.00 % = TOTAL OXIDE | |||
| Empirical Formula: |
Mg3Si4O10(OH)2 | ||
| Environment: |
Hydrothermal alteration of non-aluminous magnesian silicates. | ||
| IMA Status: |
Valid Species (Pre-IMA) 1546 | ||
| Locality: |
Common world wide. Link to MinDat.org Location Data. | ||
| Name Origin: |
From the Arabic. | ||
| Synonym: |
Kerolite | ||
| Magnesium Talc | |||
| Soapstone | |||
| Steatite - massive | |||
Talc Image | |||
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Images:
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Talc Crystallography |
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| Axial Ratios: |
a:b:c =0.5778:1:2.0668 | ||
| Cell Dimensions: |
a = 5.27, b = 9.12, c = 18.85, Z = 4; beta = 100.016° V = 892.17 Den(Calc)= 2.82 | ||
| Crystal System: |
Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/c | ||
| X Ray Diffraction: |
By Intensity(I/Io): 9.35(1), 1.53(0.55), 4.59(0.45), | ||
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Crystal Structure:
Mouse |
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Physical Properties of Talc |
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| Cleavage: |
[001] Perfect | ||
| Color: |
Pale green, White, Gray white, Yellowish white, Brownish white. | ||
| Density: |
2.7 - 2.8, Average = 2.75 | ||
| Diaphaniety: |
Translucent | ||
| Fracture: |
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern. | ||
| Habit: |
Foliated - Two dimensional platy forms. | ||
| Habit: |
Massive - Uniformly indistinguishable crystals forming large masses. | ||
| Habit: |
Scaly - Morphology like fish scales. | ||
| Hardness: |
1 - Talc | ||
| Luminescence: |
Fluorescent. | ||
| Luster: |
Vitreous - Pearly | ||
| Streak: |
white | ||
Optical Properties of Talc |
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| Gladstone-Dale: |
CI meas= 0.018 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= 0.042 (Good) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2028,KPDmeas= 0.208,KC= 0.2117 |
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| Optical Data: |
Biaxial (-), a=1.538-1.55, b=1.575-1.594, g=1.575-1.6, bire=0.0370-0.0500, 2V(Calc)=0-38, 2V(Meas)=0-30. Dispersion noticeable, r > v. | ||
| Pleochroism (x): |
colorless. | ||
| Pleochroism (y): |
pale green. | ||
| Pleochroism (z): |
pale green. | ||
Calculated Properties of Talc |
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| Electron Density: |
relectron=2.76 gm/cc |
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| Fermion Index |
Fermion Index = 0.0333 Boson Index = 0.9667 |
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| Photoelectric: |
PETalc = 1.57 barns/electron |
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Talc is Not Radioactive |
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Talc Classification |
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| Dana Class: |
71.2.1.3 (71)Phyllosilicate Sheets of Six-Membered Rings | ||
| (71.2)with 2:1 Layers | |||
| (71.2.1)Pyrophyllite-talc group | |||
| Strunz Class: |
VIII/H.09-40 VIII - Silicates | ||
| VIII/H - Phyllosilicates (layered) Mica like layered silicates with [Si4O10]4- and related groups | |||
| VIII/H.09 - Talc series | |||
Other Talc Information |
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| References: |
NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65) | ||
| See Also: |
Links to other databases for Talc : 1 - Am. Min. Crystal Structure Database 2 - Amethyst Galleries' Mineral Gallery 3 - Athena 4 - EUROmin Project 5 - Ecole des Mines de Paris 6 - Franklin Minerals(Dunn) 7 - Franklin Minerals(Palache) 8 - Glendale Community College 9 - Google Images 10 - Google Scholar 11 - Handbook of Mineralogy (MinSocAm) 12 - Handbook of Mineralogy (UofA) 13 - HyperPhysics 14 - MinDAT 15 - MinMax(Deutsch) 16 - MinMax(English) 17 - Mineralienatlas (Deutsch) 18 - Minerals in Thin Section-University of North Carolina 19 - Minerals in Thin Sections-Humboldt State 20 - QUT Mineral Atlas 21 - Ruff.Info 22 - Scandinavian mineral gallery 23 - UCLA - Petrography Thin-Sections 24 - WWW-MINCRYST 25 - YupRocks Search for Talc using: Visit our Advertisers for Talc : AA Mineral SpecimensB & L Fine Minerals Dan Weinrich Fine Minerals Dan Weinrich Auctions Excalibur Minerals Exceptional Minerals Fabre Minerals Greenside Minerals Heliodor John Betts Fine Minerals Mason's Minerals Mineral News Mineral of the Month Club MineralsWeb Fine Minerals The GeoZone Wrights Rock Shop Translate Talc Mineral Data : Ask about Talc here : Print or Cut-and-Paste your Talc Specimen Label here :
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