Sepiolite Mineral Data

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General Sepiolite Information

Chemical Formula:

Mg4Si6O15(OH)2•6(H2O)

Composition:

Molecular Weight = 613.82 gm

Magnesium 15.84 % Mg 26.26 % MgO

Silicon 27.45 % Si 58.73 % SiO₂

Hydrogen 1.97 % H 17.61 % H₂O

Oxygen 54.74 % O

______ ______

100.00 % 102.61 % = TOTAL OXIDE

Empirical Formula:

Mg₄Si₆O₁₅•6(H₂O)

Environment:

Secondary mineral associated with serpentine. Can precipitate from alkali saline waters in arid environments.

IMA Status:

Valid Species (Pre-IMA) 1847

Locality:

Eski Shehr, Asia Minor. Link to MinDat.org Location Data.

Name Origin:

From the Greek, sepia - "cuttlefish" and lithos - "stone." From the German, meerschaum meaning "sea froth."

Name Pronunciation:

Sepiolite + Pronunciation

Synonym:

ICSD 31142

Meerschaum

PDF 26-1226

Sea Foam

Sepiolite Image

Images:

Sepiolite

Comments: Sectile to chalky massive sepiolite.
Location: Pinos Altos, Grant County, New Mexico. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Sepiolite Crystallography

Axial Ratios:

a:b:c =0.4996:1:0.1964

Cell Dimensions:

a = 13.43, b = 26.88, c = 5.281, Z = 4; V = 1,906.43 Den(Calc)= 2.14

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnan

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 12.3(1), 2.58(0.6), 4.4(0.35),

Crystal Structure:

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Post J E , Bish D L , Heaney P J , American Mineralogist , 92 (2007) p.91-97, Synchrotron powder X-ray diffraction study of the structure and dehydration, behavior of sepiolite, Sample: T = 742 K, Locality: Durango, Mexico

Physical Properties of Sepiolite

Cleavage:

{???} Perfect

Color:

Grayish white, Yellowish white, Bluish green white, Reddish white, Gray.

Density:

Diaphaneity:

Opaque

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Habit:

Fibrous - Crystals made up of fibers.

Hardness:

2 - Gypsum

Luminescence:

Non-fluorescent.

Luster:

Earthy (Dull)

Streak:

white

Optical Properties of Sepiolite

Gladstone-Dale:

CI meas= -0.116 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.043 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2446,KPDmeas= 0.2617,KC= 0.2346
Ncalc = 1.47 - 1.5

Optical Data:

Biaxial (-), a=1.52, b=1.5202, g=1.53, bire=0.0100, 2V(Calc)=18, 2V(Meas)=20-70. Dispersion none.

Calculated Properties of Sepiolite

Electron Density:

Bulk Density (Electron Density)=2.18 gm/cc
note: Specific Gravity of Sepiolite =2.14 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Sepiolite= 1.43 barns/electron
U=PE_Sepiolite x rElectron Density= 3.12 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Sepiolite is Not Radioactive

Sepiolite Classification

Dana Class:

74.03.01b.01 (74)Phyllosilicate Modulated Layers

(74.03)with joined strips

(74.03.01b)Palygorskite-sepiolite group (Sepiolite subgroup)

74.03.01b.01 Sepiolite Mg4Si6O15(OH)2•6(H2O) Pnan 2/m 2/m 2/m

74.03.01b.02 Falcondoite (Ni,Mg)4Si6O15(OH)2•6(H2O) Pncn 2/m 2/m 2/m

74.03.01b.03 Loughlinite Na2Mg3Si6O16•8(H2O) Unk Ortho

Strunz Class:

09.EE.25 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.EE -Single tetrahedral nets of 6-membered rings

09.EE.25 Falcondoite (Ni,Mg)4Si6O15(OH)2•6(H2O) Pncn 2/m 2/m 2/m

09.EE.25 Loughlinite Na2Mg3Si6O16•8(H2O) Unk Ortho

09.EE.25 Kalifersite! (K,Na)5Fe7Si20O50(OH)6•12(H2O) P1 1

09.EE.25 Sepiolite Mg4Si6O15(OH)2•6(H2O) Pnan 2/m 2/m 2/m

Other Sepiolite Information

References:

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

See Also:

Links to other databases for Sepiolite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - Franklin Minerals(Dunn)
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - MinDAT
14 - Mineralienatlas (Deutsch)
15 - Online Mineral Museum
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - YupRocks

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Ask about Sepiolite here :
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Mindat.org's Discussion Groups
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Print or Cut-and-Paste your Sepiolite Specimen Label here :

Sepiolite

Mg4Si6O15(OH)2•6(H2O)
Dana No: 74.03.01b.01 Strunz No: 09.EE.25
Locality:

Notes: