Burkeite
A valid IMA mineral species - grandfathered
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About Burkeite
Formula:
Na6(CO3)(SO4)2
Colour:
White, light buff, grayish; colourless in transmitted light.
Lustre:
Vitreous, Greasy
Hardness:
3½
Specific Gravity:
2.57
Crystal System:
Orthorhombic
Name:
Named in 1935 by William Frederick Foshag in honor of William Edmund Burke [June 9, 1880 Mayfield, Santa Clara County, California, USA - November 17, 1960 Carson City, Nevada, USA], chemical engineer and director of research of the American Potash and Chemical Corporation, who discovered the synthetic salt in 1921. Early in his career, he was a chemist for the Hawaiian Sugar Planters Association.
Type Locality:
This page provides mineralogical data about Burkeite.
Unique Identifiers
Mindat ID:
805
Long-form identifier:
mindat:1:1:805:3
Similar Names
| Barikaite | A valid IMA mineral species | Ag3Pb10(Sb8As11)S40 |
IMA Classification of Burkeite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Na4(S6+O4)(CO3)
Classification of Burkeite
7.BD.25
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
D : With only large cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
D : With only large cations
32.1.1.1
32 : COMPOUND SULFATES
1 : Anhydrous Compound Sulfates
32 : COMPOUND SULFATES
1 : Anhydrous Compound Sulfates
12.2.1
12 : Carbonates with other anions
2 : Carbonates with sulphate
12 : Carbonates with other anions
2 : Carbonates with sulphate
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 |
|---|---|---|
| Bke | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Burkeite
Vitreous, Greasy
Transparency:
Transparent
Colour:
White, light buff, grayish; colourless in transmitted light.
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Fracture:
Conchoidal
Density:
2.57 g/cm3 (Measured) 2.61 g/cm3 (Calculated)
Optical Data of Burkeite
Type:
Biaxial (-)
RI values:
nα = 1.448 nβ = 1.489 nγ = 1.493
2V:
Measured: 34° , Calculated: 32°
Max. Birefringence:
δ = 0.045
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:
Moderate (negative)
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v distinct
Chemistry of Burkeite
Mindat Formula:
Na6(CO3)(SO4)2
Element Weights:
Elements listed:
Crystallography of Burkeite
Crystal System:
Orthorhombic
Cell Parameters:
a = 7.05 Å, b = 9.21 Å, c = 5.16 Å
Ratio:
a:b:c = 0.765 : 1 : 0.56
Unit Cell V:
335.04 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals tabular {100}, with narrow faces of {010}, {110}, and {001}. Crystals faces rough and uneven. Also as reticulated aggregates of platy crystals; pea-shaped nodules; irregular masses.
Twinning:
Commonly as X-shaped penetration twins with {110} as the twin plane and b^_b ~ 59°42'. The re-entrant angles are partially filled with small, rough crystals in apparent random position.
Comment:
Point Group: mm2 or 222; Space Group: Pmnm (supercell).
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) |
|---|---|---|---|---|---|---|---|
| 0014825 | Burkeite | Giuseppetti G, Mazzi F, Tadini C (1988) The crystal structure of synthetic burkeite Sample C Note sign of y-coordinate for O3 and O5 altered to reproduce reported bond lengths Neues Jahrbuch fur Mineralogie, Monatshefte 1988 203-221 | 1988 | synthetic | 0 | 293 | |
| 0014824 | Burkeite | Giuseppetti G, Mazzi F, Tadini C (1988) The crystal structure of synthetic burkeite Sample B Note sign of y-coordinate for O3 and O5 altered to reproduce reported bond lengths Neues Jahrbuch fur Mineralogie, Monatshefte 1988 203-221 | 1988 | synthetic | 0 | 293 | |
| 0014823 | Burkeite | Giuseppetti G, Mazzi F, Tadini C (1988) The crystal structure of synthetic burkeite Na4SO4(CO3)t(SO4)1-t Sample A Note sign of y-coordinate for O3 and O5 altered to reproduce reported bond lengths Neues Jahrbuch fur Mineralogie, Monatshefte 1988 203-221 | 1988 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.801 Å | (100) |
| 3.526 Å | (80) |
| 3.795 Å | (75) |
| 2.640 Å | (75) |
| 2.583 Å | (75) |
| 2.777 Å | (55) |
| 3.854 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) | |
| Stage 7: Great Oxidation Event | <2.4 |
| 45a : [Sulfates, arsenates, selenates, antimonates] | |
| 45b : [Other oxidized fumarolic minerals] |
Type Occurrence of Burkeite
General Appearance of Type Material:
as reticulated aggregates, mulberrylike nodules, commonly massive.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 97277, 102866–102872.
Geological Setting of Type Material:
Clay stratum in a lacustrine salt deposit.
Associated Minerals at Type Locality:
Synonyms of Burkeite
Other Language Names for Burkeite
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 7.BD. | Hasanovite | KNa(MoO2)(SO4)2 |
| 7.BD. | Kennygayite | [Pb4O2(OH)2](SO4) |
| 7.BD. | Adanite | Pb2(Te4+O3)(SO4) |
| 7.BD. | Cadsulfohite | Cd2(SO4)(OH)2 |
| 7.BD. | Hyblerite | Pb4Bi2(SO4)2(CO3)O4 |
| 7.BD. | Zanelliite | PbCu9[AsO3.5(OH)0.5]2(AsO4)2(OH)9(H2O)3 |
| 7.BD. | Evanichite | Pb6Cr3+(Cr6+O4)2(SO4)(OH)7FCl |
| 7.BD.05 | Sulphohalite | Na6(SO4)2FCl |
| 7.BD.10 | Galeite | Na15(SO4)5F4Cl |
| 7.BD.10 | Schairerite | Na21(SO4)7ClF6 |
| 7.BD.15 | Kogarkoite | Na3(SO4)F |
| 7.BD.20 | Aiolosite | Na4Bi(SO4)3Cl |
| 7.BD.20 | Caracolite | Na3Pb2(SO4)3Cl |
| 7.BD.20 | Cesanite | Na3Ca2(SO4)3(OH) |
| 7.BD.30 | Hanksite | Na22K(SO4)9(CO3)2Cl |
| 7.BD.35 | Cannonite | Bi2(SO4)O(OH)2 |
| 7.BD.40 | Lanarkite | Pb2(SO4)O |
| 7.BD.45 | Grandreefite | Pb2(SO4)F2 |
| 7.BD.50 | Itoite | Pb3Ge4+(SO4)2O2(OH)2 |
| 7.BD.55 | Chiluite | Bi3Te6+Mo6+O10.5 |
| 7.BD.60 | Hectorfloresite | Na9(SO4)4(IO3) |
| 7.BD.65 | Pseudograndreefite | Pb6(SO4)F10 |
| 7.BD.70 | Sundiusite | Pb10(SO4)O8Cl2 |
Other Information
Notes:
Totally soluble in cold water.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Burkeite
mindat.org URL:
https://www.mindat.org/min-805.html
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References for Burkeite
Localities for Burkeite
Showing 58 localities.
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The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
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Wadi El-Natrun depression, Beheira Governorate, Egypt