Ettringite Mineral Data

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

Name Pronunciation:

Ettringite + Pronunciation

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),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Moore A E , Taylor H F W , Acta Crystallographica, Section B , 26 (1970) p.386-393, Crystal structure of ettringite, Locality: Scawt Hill, Northern Ireland

Physical Properties of Ettringite

Cleavage:

{1010} Perfect

Color:

Colorless, White.

Density:

1.8

Diaphaneity:

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
Ncalc = 1.47

Optical Data:

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

Calculated Properties of Ettringite

Electron Density:

Bulk Density (Electron Density)=1.89 gm/cc
note: Specific Gravity of Ettringite =1.80 gm/cc.

Fermion Index:

Fermion Index = 0.0011471359
Boson Index = 0.9988528641

Photoelectric:

PE_Ettringite= 2.97 barns/electron
U=PE_Ettringite x rElectron Density= 5.60 barns/cc.

Radioactivity:

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

Ettringite Classification

Dana Class:

31.10.02.01 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.10)miscellaneous

(31.10.02)Dana Group

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

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

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

Strunz Class:

07.DG.15 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.15 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12•26(H2O) P 6₃/mmc 6/m 2/m 2/m

07.DG.15 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12•26(H2O) P 3₁c 3m

07.DG.15 Ettringite Ca6Al2(SO4)3(OH)12•26(H2O) P 6₃/mmc 6/m 2/m 2/m

07.DG.15 Jouravskite Ca3Mn(SO4,CO3)2(OH)6•12(H2O) P 6₃/m 6/m

07.DG.15 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12•25(H2O) P 3₁c 3m

07.DG.15 Thaumasite Ca3Si(CO3)(SO4)(OH)6•12(H2O) P 6₃/m 6/m

07.DG.15 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6•12(H2O) P 3₁c 3m

07.DG.15 Carraraite! Ca3Ge(OH)6(SO4)(CO3)•12H2O P 6₃/m, or P 6₃ Hex

Other Ettringite Information

References:

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

See Also:

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

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Print or Cut-and-Paste your Ettringite Specimen Label here :

Ettringite

Ca6Al2(SO4)3(OH)12•26(H2O)
Dana No: 31.10.02.01 Strunz No: 07.DG.15
Locality:

Notes: