Kurgantaite
A valid IMA mineral species - grandfathered
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About Kurgantaite
Formula:
CaSr[B5O9]Cl · H2O
Colour:
Colourless to white
Lustre:
Vitreous
Hardness:
6 - 6½
Specific Gravity:
2.99
Crystal System:
Triclinic
Member of:
Name:
Named for the type locality, Kargan-tau, Kazakhstan.
Hilgardite Group.
1952 described as a new mineral, 1982 discredited as a strontian variety of tyretskite, 2000 revalidated and approved by the IMA.
1952 described as a new mineral, 1982 discredited as a strontian variety of tyretskite, 2000 revalidated and approved by the IMA.
Unique Identifiers
Mindat ID:
8212
Long-form identifier:
mindat:1:1:8212:5
IMA Classification of Kurgantaite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaSrB5O9Cl·H2O
Approval year:
2002
First published:
1952
Approval history:
IMA Code 00-B - Kurgantaite revalidated (2002).
Classification of Kurgantaite
6.ED.05
6 : BORATES
E : Pentaborates
D : Tekto-pentaborates
6 : BORATES
E : Pentaborates
D : Tekto-pentaborates
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 |
|---|---|---|
| Kga | 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 Kurgantaite
Vitreous
Transparency:
Transparent
Colour:
Colourless to white
Streak:
White
Hardness:
6 - 6½ on Mohs scale
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
Imperfect/Fair
Fracture:
Irregular/Uneven
Density:
2.99 g/cm3 (Measured) 3.04 g/cm3 (Calculated)
Optical Data of Kurgantaite
Type:
Biaxial (+)
RI values:
nα = 1.637 nβ = 1.638 nγ = 1.675
2V:
Calculated: 19°
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:
Moderate
Pleochroism:
Non-pleochroic
Chemistry of Kurgantaite
Mindat Formula:
CaSr[B5O9]Cl · H2O
Element Weights:
Crystallography of Kurgantaite
Crystal System:
Triclinic
Class (H-M):
1 - Pedial
Space Group:
P1
Cell Parameters:
a = 6.573 Å, b = 6.445 Å, c = 6.369 Å
α = 60.995°, β = 61.257°, γ = 77.191°
α = 60.995°, β = 61.257°, γ = 77.191°
Ratio:
a:b:c = 1.02 : 1 : 0.988
Unit Cell V:
206.9 ų
Z:
1
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.69 Å | (80) |
| 3.22 Å | (90) |
| 3.13 Å | (70) |
| 2.92 Å | (100) |
| 2.84 Å | (90) |
| 2.79 Å | (80) |
| 2.14 Å | (70) |
| 2.07 Å | (70) |
Comments:
Chelkar salt dome, Kazakhstan. The data are from Pekov et al. (2001).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Type Occurrence of Kurgantaite
General Appearance of Type Material:
Fine-grained nodules up to 4 cm across.
Place of Conservation of Type Material:
A. E. Fersman Mineralogical Museum, Moscow, Russia (neotype).
Geological Setting of Type Material:
In a borate deposit.
Associated Minerals at Type Locality:
Synonyms of Kurgantaite
Other Language Names for Kurgantaite
Relationship of Kurgantaite to other Species
Member of:
Other Members of Hilgardite Group:
| Hilgardite | Ca2B5O9Cl · H2O | Tric. 1 : P1 |
| Leucostaurite | Pb2[B5O9]Cl · 0.5H2O | Orth. mm2 : Pnn2 |
| Tyretskite | Ca2B5O9OH · H2O | Tric. 1 : P1 |
Related Minerals - Strunz-mindat Grouping
| 6.ED.05 | Hilgardite | Ca2B5O9Cl · H2O |
| 6.ED.05 | Tyretskite | Ca2B5O9OH · H2O |
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 Kurgantaite
mindat.org URL:
https://www.mindat.org/min-8212.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Kurgantaite
Reference List:
Jambor, John L., Grew, Edward S., Roberts, Andrew C. (2002) New mineral names. American Mineralogist, 87. 1509-1513 pp.1510-1511
Localities for Kurgantaite
Showing 8 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.
Canada | |
| Grice et al. (2005) |
| Grice et al. (2002) | |
China | |
| Anthony |
Kazakhstan (TL) | |
| Pekov et al. (2001) |
| I.V. Pekov et al. (2001) +2 other references |
Russia | |
| AmMin 87:1509-1512 |
| Pekov et al. (2001) +2 other references |
| Alrosa |
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Korshunovskoye iron deposit, Zheleznogorsk-Ilimsky, Nizhneilimsky District, Irkutsk Oblast, Russia