Chelkarite
A valid IMA mineral species - grandfathered
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Formula:
CaMgB2O4(Cl,OH)2 · 5H2O Or near, with Cl:OH = 3:1
Colour:
Colorless
Specific Gravity:
2.21
Crystal System:
Orthorhombic
Name:
Named for the Chelkar salt dome, Kazakhstan, where it was discovered.
This page provides mineralogical data about Chelkarite.
Unique Identifiers
Mindat ID:
985
Long-form identifier:
mindat:1:1:985:8
IMA Classification of Chelkarite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaMgB2O4Cl2·7H2O
First published:
1968
Classification of Chelkarite
6.H0.05
6 : BORATES
H : Unclassified borates
0 :
6 : BORATES
H : Unclassified borates
0 :
26.7.2.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
7 : Miscellaneous
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
7 : Miscellaneous
10.1.15
10 : Borates with other anions
1 : Borates with halide
10 : Borates with other anions
1 : Borates with halide
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 |
|---|---|---|
| Cka | 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 Chelkarite
Transparency:
Transparent
Colour:
Colorless
Streak:
White
Cleavage:
Perfect
Parallel to elongation, so mineral breaks into needles
Parallel to elongation, so mineral breaks into needles
Fracture:
Splintery
Density:
2.21 g/cm3 (Measured) 1.96 g/cm3 (Calculated)
Optical Data of Chelkarite
Type:
Biaxial (+)
RI values:
nα = 1.520 nγ = 1.558
Max. Birefringence:
δ = 0.038
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:
None to Very Low
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.
No measured or calculated 2V is on file for this mineral, so the value used here (91°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
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.
No measured or calculated 2V is on file for this mineral, so the value used here (91°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
weak to moderate
Chemistry of Chelkarite
Mindat Formula:
CaMgB2O4(Cl,OH)2 · 5H2O Or near, with Cl:OH = 3:1
Element Weights:
Crystallography of Chelkarite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbca
Setting:
Pbca
Cell Parameters:
a = 13.69 Å, b = 20.84 Å, c = 8.26 Å
Ratio:
a:b:c = 0.657 : 1 : 0.396
Unit Cell V:
2,356.57 ų (Calculated from Unit Cell)
Z:
10
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.531 Å | (100) |
| 10.42 Å | (90) |
| 2.209 Å | (80) |
| 4.96 Å | (70) |
| 2.029 Å | (70) |
| 6.68 Å | (50) |
| 4.19 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Type Occurrence of Chelkarite
General Appearance of Type Material:
Flattened long prismatic crystals to 15 mm.
Place of Conservation of Type Material:
No designated type material.
Geological Setting of Type Material:
Carnallite-bischofite rock at a salt dome.
Associated Minerals at Type Locality:
Other Language Names for Chelkarite
Related Minerals - Strunz-mindat Grouping
| 6.H0.10 | Braitschite-(Ce) | (Ca,Na2)7(Ce,La)2B22O43 · 7H2O |
| 6.H0.15 | Satimolite | KNa2(Al5Mg2)[B12O18(OH)12](OH)6Cl4 · 4H2O |
| 6.H0.20 | Iquiqueite | K3Na4Mg(CrO4)B24O39(OH) · 12H2O |
| 6.H0.25 | Wardsmithite | Ca5Mg[B4O7]6 · 30H2O |
| 6.H0.35 | Halurgite | Mg4[B8O13(OH)2]2 · 7H2O |
| 6.H0.40 | Ekaterinite | Ca2(B4O7)(Cl,OH)2 · 2H2O |
| 6.H0.45 | Vitimite | Ca6[B14O19](SO4)(OH)14 · 5H2O |
| 6.H0.50 | Canavesite | Mg2(HBO3)(CO3) · 5H2O |
| 6.H0.55 | Qilianshanite | NaHCO3 · H3BO3 · 2H2O |
Other Information
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 Chelkarite
mindat.org URL:
https://www.mindat.org/min-985.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Chelkarite
Localities for Chelkarite
Showing 1 localities.
symbol to view information about a locality.
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.
Kazakhstan (TL) | |
| Avrova et al. (1968) +1 other reference |
