Vermiculite Mineral Data

Vermiculite Mineral Data +

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General Vermiculite Information

Chemical Formula:

(Mg,Fe++,Al)3(Al,Si)4O10(OH)2·4(H2O)

Composition:

Molecular Weight = 504.19 gm

Magnesium 8.68 % Mg 14.39 % MgO

Aluminum 23.01 % Al 43.48 % Al₂O₃

Iron 9.97 % Fe 12.82 % FeO

Silicon 5.57 % Si 11.92 % SiO₂

Hydrogen 2.00 % H 17.87 % H₂O

Oxygen 50.77 % O

______ ______

100.00 % 100.48 % = TOTAL OXIDE

Empirical Formula:

Mg_1.8Fe²⁺_0.9Al_4.3SiO₁₀(OH)₂·4(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1824

Locality:

Link to MinDat.org Location Data.

Name Origin:

From the Latin vermiculus, "little worm."

Vermiculite Image

Images:

Vermiculite

Comments: Micaceous vermiculite book.
Location: Brinton's Quarry, near West Chester, Chester County, Pennsylvania, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Vermiculite Crystallography

Axial Ratios:

a:b:c =0.5698:1:1.6218

Cell Dimensions:

a = 5.26, b = 9.23, c = 14.97, Z = 2; beta = 96.82° V = 721.65 Den(Calc)= 2.32

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

Crystal Structure:

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Gruner J W , American Mineralogist , 19 (1934) p.557-575, The structures of vermiculites and their collapse by dehydration

View Additional jPOWD Structure files for Vermiculite
[1] [2] [3] [4] [5]

Physical Properties of Vermiculite

Cleavage:

[001] Perfect

Color:

Colorless, Green, Gray white, Yellow brown.

Density:

2.3 - 2.7, Average = 2.5

Diaphaniety:

Translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Lamellar - Thin laminae producing a lamellar structure.

Habit:

Scaly - Morphology like fish scales.

Hardness:

1.5-2 - Talc-Gypsum

Luster:

Vitreous - Dull

Streak:

greenish white

Optical Properties of Vermiculite

Gladstone-Dale:

CI meas= 0.026 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.05 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2398,KPDmeas= 0.2225,KC= 0.2284

Optical Data:

Biaxial (-), a=1.525-1.561, b=1.545-1.581, g=1.545-1.581, bire=0.0200, 2V(Calc)=0, 2V(Meas)=0-8. Dispersion weak, r > v.

Pleochroism (x):

colorless or pale green.

Pleochroism (y):

pale brown, yellowish green, or brownish green.

Pleochroism (z):

pale brown, yellowish green, or brownish green.

Calculated Properties of Vermiculite

Electron Density:

r_electron=2.51 gm/cc
note: r_Vermiculite=2.50 gm/cc.

Fermion Index

Fermion Index = 0.01363
Boson Index = 0.98637

Photoelectric:

PE_Vermiculite= 4.01 barns/electron
U=PE_Vermiculite x r_electron= 10.06 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Vermiculite is Not Radioactive

Vermiculite Classification

Dana Class:

71.2.2d.3 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.2)with 2:1 Layers

(71.2.2d)Mica Group (Hydromica subgroup)

71.2.2d.1 Hydrobiotite [K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2]·[(Mg,Fe,Al)3(Si,Al)4O10(OH)2·4(H2O)] C 2/m 2/m

71.2.2d.2 Illite* (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m

71.2.2d.3 Vermiculite (Mg,Fe,Al)3(Al,Si)4O10(OH)2·4(H2O) C 2/m 2/m

71.2.2d.4 Brammallite* (Na,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/c 2/m

Strunz Class:

VIII/H.21-10 VIII - Silicates

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

VIII/H.21 - Vermiculite series

VIII/H.21-10 Vermiculite (Mg,Fe,Al)3(Al,Si)4O10(OH)2·4(H2O) C 2/m 2/m

Other Vermiculite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Vermiculite

(Mg,Fe++,Al)3(Al,Si)4O10(OH)2·4(H2O)
Dana No: 71.2.2d.3 Strunz No: VIII/H.21-10
Locality:

Notes: