Ettringite Mineral Data

Ettringite Mineral Data +

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General Ettringite Information

Chemical Formula:

Ca6Al2(SO4)3(OH)12·26(H2O)

Composition:

Molecular Weight = 1,255.11 gm

Calcium 19.16 % Ca 26.81 % CaO

Aluminum 4.30 % Al 8.12 % Al₂O₃

Hydrogen 5.14 % H 45.93 % H₂O

Sulfur 7.66 % S 19.14 % SO₃

Oxygen 63.74 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₆Al₂(SO₄)₃(OH)₁₂·26(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1874

Locality:

Ettringer Bellerberg, Ettringen, Mayen, Eifel, Rheinland-Pfalz, Germany Link to MinDat.org Location Data.

Name Origin:

Named for the locality

Synonym:

ICSD 16045

PDF 41-1451

Ettringite Image

Images:

Ettringite

Comments: Small glassy whitish micro crystals of ettringite on a white powdery matrix.
Location: Ettringen, Eifel, Allemagne, Germany. Scale: 2.5 x 1 x 2 cm.
© John Veevaert

Images:

Ettringite

Comments: Doubly-terminated crystals of glassy yellow ettringite on matrix.
Location: N'Chwaning Mine, near Kuruman, South Africa. Scale: Crystal size 4 cm.
© Rob Lavinsky

Ettringite Crystallography

Axial Ratios:

a:c = 1:0.95458

Cell Dimensions:

a = 22.46, c = 21.44, Z = 8; V = 9,366.45 Den(Calc)= 1.78

Crystal System:

Hexagonal - Dihexagonal DipyramidalH-M Symbol (6/m 2/m 2/m) Space Group: P 6₃/mmc

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

By Intensity(I/I_o): 9.65(1), 5.58(0.8), 3.21(0.6),

Physical Properties of Ettringite

Cleavage:

[1010] Perfect

Color:

Colorless, White.

Density:

1.8

Diaphaniety:

Transparent

Habit:

Acicular - Occurs as needle-like crystals.

Hardness:

2-2.5 - Gypsum-Finger Nail

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Ettringite

Gladstone-Dale:

CI meas= -0.014 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.026 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2699,KPDmeas= 0.2669,KC= 0.2632

Optical Data:

Uniaxial (-), e=1.47, w=1.491, bire=0.0210.

Calculated Properties of Ettringite

Electron Density:

r_electron=1.89 gm/cc
note: r_Ettringite=1.80 gm/cc.

Fermion Index

Fermion Index = 0.00114
Boson Index = 0.99886

Photoelectric:

PE_Ettringite= 2.97 barns/electron
U=PE_Ettringite x r_electron= 5.60 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ettringite is Not Radioactive

Ettringite Classification

Dana Class:

31.10.2.1 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.10)miscellaneous

(31.10.2)Dana Group

31.10.2.1 Ettringite Ca6Al2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

31.10.2.2 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

31.10.2.3 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6·12(H2O) P 3₁c 3m

Strunz Class:

VI/D.13-10 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/D - Water-bearing sulfates with unfamiliar anions. cations of medium and very big size

VI/D.13 - Ettringite group, Ettringite - Sturmanite

VI/D.13-10 Ettringite Ca6Al2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

VI/D.13-20 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

VI/D.13-30 Jouravskite Ca3Mn(SO4,CO3)2(OH)6·12(H2O) P 6₃/m 6/m

VI/D.13-35 Carraraite! Ca3Ge(OH)6(SO4)(CO3)·12H2O P 6₃/m, or P 6₃ Hex

VI/D.13-40 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12·26(H2O) P 3₁c 3m

VI/D.13-50 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12·25(H2O) P 3₁c 3m

VI/D.13-60 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6·12(H2O) P 3₁c 3m

Other Ettringite Information

References:

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

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Ettringite

Ca6Al2(SO4)3(OH)12·26(H2O)
Dana No: 31.10.2.1 Strunz No: VI/D.13-10
Locality:

Notes: