Chessexite Mineral Data

General Chessexite Information

Chemical Formula:

(K,Na)4Ca2Mg3Al8(SiO4)2(SO4)10(OH)10•40(H2O)

Composition:

Molecular Weight = 2,528.59 gm

Potassium 3.09 % K 3.73 % K₂O

Sodium 1.82 % Na 2.45 % Na₂O

Calcium 3.17 % Ca 4.44 % CaO

Magnesium 2.88 % Mg 4.78 % MgO

Aluminum 8.54 % Al 16.13 % Al₂O₃

Silicon 2.22 % Si 4.75 % SiO₂

Hydrogen 3.59 % H 32.06 % H₂O

Sulfur 12.68 % S 31.66 % SO₃

Oxygen 62.01 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

K₂Na₂Ca₂Mg₃Al₈(SiO₄)₂(SO₄)₁₀(OH)₁₀ï¿½40(H₂O)

Environment:

Coating fluorite.

IMA Status:

Approved IMA 1982

Locality:

Maine mine, Autun, Saone et Loire, France. Link to MinDat.org Location Data.

Name Origin:

Named for Ronald Chessex (1929-), Swiss petrologist and professor, University of Geneva.

Chessexite Crystallography

Axial Ratios:

a:b:c =0.4899:1:0.3572

Cell Dimensions:

a = 13.7, b = 27.96, c = 9.99, Z = 2; V = 3,826.69 Den(Calc)= 2.19

Crystal System:

Orthorhombic Space Group: Unk

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

By Intensity(I/I_o): 13.91(1), 4.85(0.9), 3.982(0.6),

Physical Properties of Chessexite

Cleavage:

{???} Indistinct

Color:

White.

Density:

2.21

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Habit:

Platy - Sheet forms (e.g. micas).

Luster:

Silky

Streak:

white

Optical Properties of Chessexite

Gladstone-Dale:

CI meas= 0.12 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.112 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2125,KPDmeas= 0.2106,KC= 0.2392
Ncalc = 1.52 - 1.53

Optical Data:

Biaxial (+), a=1.456, b=1.46, g=1.48, bire=0.0240, 2V(Calc)=50, 2V(Meas)=47.

Calculated Properties of Chessexite

Electron Density:

Bulk Density (Electron Density)=2.26 gm/cc
note: Specific Gravity of Chessexite =2.19 gm/cc.

Fermion Index:

Fermion Index = 0.0052216723
Boson Index = 0.9947783277

Photoelectric:

PE_Chessexite= 1.95 barns/electron
U=PE_Chessexite x r_electron= 4.40 barns/cc.

Radioactivity:

GRapi = 45.95 (Gamma Ray American Petroleum Institute Units)
Concentration of Chessexite per GRapi unit = 2.18 (%)

Estimated Radioactivity from Chessexite - barely detectable

Chessexite Classification

Dana Class:

32.04.06.01 (32)Compound Sulfates

(32.04)(hydrous) with poly-anionic formula

(32.04.06)Dana Group

32.04.06.01 Chessexite (K,Na)4Ca2Mg3Al8(SiO4)2(SO4)10(OH)10•40(H2O) Unk Ortho

Strunz Class:

07.DG.35 07 - SULFATES (SELENATES, TELLURATES)

07.D - Sulfates (selenates, etc.) with additional anions, with H2O

07.DG -With large and medium sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3

07.DG.35 Chessexite (K,Na)4Ca2Mg3Al8(SiO4)2(SO4)10(OH)10•40(H2O) Unk Ortho

Other Chessexite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

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

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Chessexite

(K,Na)4Ca2Mg3Al8(SiO4)2(SO4)10(OH)10•40(H2O)
Dana No: 32.04.06.01 Strunz No: 07.DG.35
Locality:

Notes:

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