Ekatite Mineral Data

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General Ekatite Information

Chemical Formula:

(Fe+++,Fe++,Zn)12(OH)6[AsO3]6[AsO3,HOSiO3]2

Composition:

Molecular Weight = 1,761.38 gm

Zinc 2.97 % Zn 3.70 % ZnO

Iron 35.51 % Fe 21.21 % FeO / 27.20 % Fe₂O₃

Silicon 0.96 % Si 2.05 % SiO₂

Arsenic 32.33 % As 42.68 % As₂O₃

Hydrogen 0.35 % H 3.12 % H₂O

Oxygen 27.89 % O

______ ______

100.00 % 99.95 % = TOTAL OXIDE

Empirical Formula:

Fe³⁺₆Fe²⁺_5.2Zn_0.8(OH)_6.1(AsO₃)_7.6(SiO₃)_0.6

Environment:

Oxidation product occurring on a matrix of chalcocite and etched quartz.

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

Tsumeb mine, Namibia. Link to MinDat.org Location Data.

Name Origin:

Named for Dieter Ekat (1935-1996), Namibian mining engineer.

Synonym:

IMA1998-024

Ekatite Image

Images:

Ekatite

Comments: Divergent spray of dark brown acicular ekatite crystals.
Location: Tsumeb mine, Namibia.. Scale: 15 mm Tall.
© William Pinch

Ekatite Crystallography

Axial Ratios:

a:c = 1:0.39544

Cell Dimensions:

a = 12.773, c = 5.051, Z = 1; V = 713.66 Den(Calc)= 4.10

Crystal System:

Hexagonal - Dihexagonal PyramidalH-M Symbol (6mm) Space Group: P 6₃mc

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

By Intensity(I/I_o): 3.22(1)(211,220), 2.42(0.7)(401,410), 6.37(0.5)(110),1.788(0.4), 2.531(0.4), 2.766(0.3)(400), 11.11(0.3)(100), 1.507(0.3)(701,431), 1.672(0.3)(521),

Crystal Structure:

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drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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Keller P , European Journal of Mineralogy , 13 (2001) p.769-777, Ekatite, (Fe3+,Fe2+,Zn)12(OH)6[AsO3]6[AsO3,HOSiO3]2, a new mineral, from Tsumeb, Namibia, and its crystal structure, Locality: Tsumeb, Namibia

Physical Properties of Ekatite

Cleavage:

None

Color:

Brownish black.

Diaphaneity:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

brown

Optical Properties of Ekatite

Gladstone-Dale:

CI calc= -0.024 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2524,KC= 0.2466
Ncalc = 2.01

Optical Data:

Uniaxial (+), w=1.99, e=2.08, bire=0.0900.

Calculated Properties of Ekatite

Electron Density:

Bulk Density (Electron Density)=3.85 gm/cc
note: Specific Gravity of Ekatite =4.10 gm/cc.

Fermion Index:

Fermion Index = 0.0093271825
Boson Index = 0.9906728175

Photoelectric:

PE_Ekatite= 34.84 barns/electron
U=PE_Ekatite x rElectron Density= 134.00 barns/cc.

Radioactivity:

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

Ekatite Classification

Dana Class:

43.04.10.02 (43)Compound Phosphates, etc.

(43.04)(Anhydrous Compound Anions With Hydroxyl or Halogen)

(43.04.10)Kraisslite Group

43.04.10.01 Kraisslite (Mn,Mg)24Zn3Fe(AsO3)2(AsO4)3(SiO4)6(OH)18 P 6₃22 6 2 2

43.04.10.02 Ekatite! (Fe,Fe,Zn)12(OH)6[AsO3]6[AsO3,HOSiO3]2 P 6₃mc 6mm

Strunz Class:

04.JB.75 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.J - Arsenites, Antimonites, Bismuthites, Sulfites,

04.JB -Arsenites, antimonites, bismuthites; with additional anions, without H2O

04.JB.75 Ekatite! (Fe,Fe,Zn)12(OH)6[AsO3]6[AsO3,HOSiO3]2 P 6₃mc 6mm

Other Ekatite Information

References:

NAME( AmMin, Vol 87, p 355) PHYS. PROP.(AmMin, Vol 87, p 355) OPTIC PROP.(AmMin, Vol 87, p 355)

See Also:

Links to other databases for Ekatite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

Search for Ekatite using:

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Ask about Ekatite here :
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Print or Cut-and-Paste your Ekatite Specimen Label here :

Ekatite

(Fe+++,Fe++,Zn)12(OH)6[AsO3]6[AsO3,HOSiO3]2
Dana No: 43.04.10.02 Strunz No: 04.JB.75
Locality:

Notes: