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Ekatite
A valid IMA mineral species
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About Ekatite
Formula:
(Fe3+,Fe2+,Zn)12(AsO3)6(AsO3,HSiO4)2(OH)6
Colour:
Brownish black
Lustre:
Vitreous
Hardness:
3
Specific Gravity:
4.061 (Calculated)
Crystal System:
Hexagonal
Name:
Named in honor of Dieter Ekat (1935-1996), a Namibian mining engineer and owner of the Rubikon Mine.
This page provides mineralogical data about Ekatite.
Unique Identifiers
Mindat ID:
7049
Long-form identifier:
mindat:1:1:7049:8
Similar Names
IMA Classification of Ekatite
Approved
IMA Formula:
(Fe3+,Fe2+,Zn2+)12(As3+O3)6(As3+O3,SiO3OH)2(OH)6
Approval year:
1998
Classification of Ekatite
4.JB.75
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
B : Arsenites, antimonites, bismuthites; with additional anions, without H2O
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
B : Arsenites, antimonites, bismuthites; with additional anions, without H2O
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Ekt | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Ekatite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Ekatite
Vitreous
Transparency:
Translucent
Colour:
Brownish black
Streak:
Brown
Hardness:
3 on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Density:
4.061 g/cm3 (Calculated)
Optical Data of Ekatite
Type:
Uniaxial (+)
RI values:
nω = 1.99 nε = 2.08
Max. Birefringence:
δ = 0.090
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Strong
Comments:
O = dark brownish black, E = medium brown, both with a greenish tint
Comments:
n(calc.) = 2.013
Chemistry of Ekatite
Mindat Formula:
(Fe3+,Fe2+,Zn)12(AsO3)6(AsO3,HSiO4)2(OH)6
Element Weights:
Crystallography of Ekatite
Crystal System:
Hexagonal
Class (H-M):
6mm - Dihexagonal Pyramidal
Space Group:
P63mc
Cell Parameters:
a = 12.773(2) Å, c = 5.051(1) Å
Ratio:
a:c = 1 : 0.395
Unit Cell V:
713.66 ų (Calculated from Unit Cell)
Z:
1
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0006895 | Ekatite | Keller P (2001) Ekatite, (Fe3+,Fe2+,Zn)12(OH)6[AsO3]6[AsO3,HOSiO3]2, a new mineral from Tsumeb, Namibia, and its crystal structure European Journal of Mineralogy 13 769-777 | 2001 | Tsumeb, Namibia | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.220 Å | (10) |
| 2.420 Å | (7) |
| 6.37 Å | (5) |
| 11.11 Å | (3) |
| 2.766 Å | (3) |
| 1.867 Å | (3) |
| 1.672 Å | (3) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Ekatite
General Appearance of Type Material:
sprays of acicular crystals to 2 mm
Place of Conservation of Type Material:
Institute for Mineralogy and Crystal Chemistry, University of Stuttgart, Germany (NM20).
Associated Minerals at Type Locality:
Synonyms of Ekatite
Other Language Names for Ekatite
Related Minerals - Strunz-mindat Grouping
| 4.JB. | Cuyaite | Ca2Mn3+As3+14O24Cl |
| 4.JB. | Brattforsite | Mn19(AsO 3)12Cl2 |
| 4.JB.05 | Fetiasite | (Fe3+,Fe2+,Ti)3(As2O5)O2 |
| 4.JB.10 | Manganarsite | Mn3(As2O4)(OH)4 |
| 4.JB.15 | 'UM1984-09-AsO:ClHMn' | Mn10As6O18(OH)Cl |
| 4.JB.15 | Magnussonite | Mn2+10(As3+O3)6(OH,Cl)2 |
| 4.JB.20 | Armangite | Mn2+26(AsO3)14(HAsO3)4(CO3) |
| 4.JB.25 | Nanlingite | Na(Ca5Li)Mg12(AsO3)2[Fe(AsO3)6]F14 |
| 4.JB.30 | Asbecasite | Ca3(Ti,Sn4+)Be2(AsO3)6(SiO4)2 |
| 4.JB.35 | Stenhuggarite | CaFeSb(AsO3)2O |
| 4.JB.40 | Trigonite | Pb3Mn2+(AsO3)2(HAsO3) |
| 4.JB.45 | Finnemanite | Pb5(AsO3)3Cl |
| 4.JB.50 | Gebhardite | Pb8(As2O5)2OCl6 |
| 4.JB.55 | Graeserite | Fe3+4Ti3As3+O13(OH) |
| 4.JB.55 | Tomichite | (V,Fe)4Ti3AsO13(OH) |
| 4.JB.55 | Derbylite | Fe3+4Ti3Sb3+O13(OH) |
| 4.JB.60 | Hemloite | (Ti,V3+,Fe3+,Al)12(As3+,Sb3+)2O23(OH) |
| 4.JB.65 | Freedite | Cu+Pb8(AsO3)2O3Cl5 |
| 4.JB.70 | Georgiadesite | Pb4(As3+O3)Cl4(OH) |
| 4.JB.75 |
Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia