Mineraller ve özellikleri Talk General Talc Information Chemical Formula: Mg3Si4O10(OH)2 Composition: Molecular Weight = 379.27 gm Magnesium 19.23 % Mg 31.88 % MgO Silicon 29.62 % Si 63.37 % SiO 2 Hydrogen 0.53 % H 4.75 % H 2 O Oxygen 50.62 % O ______ ______ 100.00 % 100.00 % = TOTAL OXIDE Empirical Formula: Mg 3Si4O 10(OH)2 Environment: Hydrothermal alteration of non-aluminous magnesian silicates. IMA Status: Valid Species (Pre-IMA) Locality: Common world wide. Link to MinDat.org Location Data. Name Origin: From the Arabic. Synonym: Kerolite Magnesium Talc Soapstone Steatite - massive Talc Crystallography 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/I o): 9.35(1), 1.53(0.55), 4.59(0.45), Physical Properties of Talc 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. Habits: Foliated - Two dimensional platy forms., Scaly - Morphology like fish scales., Massive - Uniformly indistinguishable crystals forming large masses. Hardness: 1 - Talc Luminescence: Fluorescent. Luster: Vitreous - Pearly Streak: white Optical Properties of Talc 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 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. Talc Classification Dana Class: (71)Phyllosilicate Sheets of Six-Membered Rings (71.2)with 2:1 Layers (71.2.1)Pyrophyllite-talc group Pyrophyllite Al2Si4O10(OH)2 P1 1 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m Talc Mg3Si4O10(OH)2 C 2/c 2/m Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m Minnesotaite (Fe,Mg)3Si4O10(OH)2 C1 1 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.09-40 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