Kurnakovite
A valid IMA mineral species - grandfathered
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About Kurnakovite
Nikolai S. Kurnakov
Formula:
MgB3O3(OH)5 · 5H2O
Colour:
White; colourless in transmitted light
Lustre:
Vitreous
Hardness:
2½ - 3
Specific Gravity:
1.847 - 1.852
Crystal System:
Triclinic
Member of:
Name:
Named in honor of Nikolaĭ Semenovich Kurnakov (Никола́й Семёнович Курнако́в, 6 December 1860, Nolinsk, Russia – 19 March 1941, Barvikha, USSR), mineralogist and chemist. He was one of the founders of the platinum industry in the USSR.
Type Locality:
Dimorph of:
Unique Identifiers
Mindat ID:
2295
Long-form identifier:
mindat:1:1:2295:4
IMA Classification of Kurnakovite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
MgB3O3(OH)5·5H2O
First published:
1940
Classification of Kurnakovite
6.CA.20
6 : BORATES
C : Triborates
A : Neso-triborates
6 : BORATES
C : Triborates
A : Neso-triborates
26.3.3.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
3 : Triborates
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
3 : Triborates
9.2.9
9 : Borates
2 : Borates of Be and Mg
9 : Borates
2 : Borates of Be and Mg
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 |
|---|---|---|
| Kko | 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 Kurnakovite
Vitreous
Transparency:
Transparent, Translucent
Colour:
White; colourless in transmitted light
Streak:
White
Hardness:
2½ - 3 on Mohs scale
Cleavage:
Poor/Indistinct
On {010}.
On {010}.
Density:
1.847 - 1.852 g/cm3 (Measured) 1.855 g/cm3 (Calculated)
Optical Data of Kurnakovite
Type:
Biaxial (-)
RI values:
nα = 1.488 - 1.491 nβ = 1.508 - 1.51 nγ = 1.515 - 1.525
2V:
Measured: 60° to 80°, Calculated: 60°
Max. Birefringence:
δ = 0.027 - 0.034
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:
weak r > v
Chemistry of Kurnakovite
Mindat Formula:
MgB3O3(OH)5 · 5H2O
Element Weights:
Elements listed:
Crystallography of Kurnakovite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 8.3479(1) Å, b = 10.6068(1) Å, c = 6.4447(1) Å
α = 98.846°, β = 108.981°, γ = 105.581°
α = 98.846°, β = 108.981°, γ = 105.581°
Ratio:
a:b:c = 0.787 : 1 : 0.608
Unit Cell V:
501.24 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Rough prismatic crystals to 37cm. Dense aggregates.
Twinning:
Twinned at times.
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) |
|---|---|---|---|---|---|---|---|
| 0009513 | Kurnakovite | Corazza E (1974) The crystal structure of kurnakovite: a refinement Acta Crystallographica B30 2194-2199 |  | 1974 | California, USA | 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 |
|---|---|
| 7.224 Å | (100) |
| 4.895 Å | (85) |
| 4.205 Å | (80) |
| 5.007 Å | (75) |
| 2.677 Å | (75) |
| 2.477 Å | (70) |
| 3.479 Å | (65) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Type Occurrence of Kurnakovite
General Appearance of Type Material:
Dense white aggregates.
Place of Conservation of Type Material:
Karpinskii All-Union Research Institute of Geology, St. Petersburg, Russia.
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 61590.
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 61590.
Geological Setting of Type Material:
Occurs as irregular lenses in szaibelyite, in a borate deposit.
Associated Minerals at Type Locality:
Other Language Names for Kurnakovite
Relationship of Kurnakovite to other Species
Member of:
Other Members of Inderite Group:
| Inderborite | CaMg(H3B3O7)2 · 8H2O | Mon. 2/m : B2/b |
| Inderite | MgB3O3(OH)5 · 5H2O | Mon. 2/m : P21/b |
| Inyoite | Ca(H4B3O7)(OH) · 4H2O | Mon. 2/m : P21/b |
| Meyerhofferite | CaB3O3(OH)5 · H2O | Tric. 1 : P1 |
| Solongoite | Ca2(H3B3O7)(OH)Cl | Mon. 2/m : P21/b |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 6.CA.10 | Ameghinite | Na(H4B3O7) |
| 6.CA.15 | Inderite | MgB3O3(OH)5 · 5H2O |
| 6.CA.25 | Inderborite | CaMg(H3B3O7)2 · 8H2O |
| 6.CA.30 | Meyerhofferite | CaB3O3(OH)5 · H2O |
| 6.CA.35 | Inyoite | Ca(H4B3O7)(OH) · 4H2O |
| 6.CA.40 | Solongoite | Ca2(H3B3O7)(OH)Cl |
| 6.CA.45 | Peprossiite-(Ce) | CeAl2(B3.67Si0.33)O10.67 |
| 6.CA.45 | Peprossiite-(Y) | YAl2(B3.67Si0.33)O10.67 |
| 6.CA.50 | Nifontovite | Ca3B6O6(OH)12(H2O)2 |
| 6.CA.55 | Olshanskyite | Ca2[B3O3(OH)6](OH) · 3H2O |
Other Information
Notes:
Insoluble in water. Soluble in warm acids.
With a blowpipe it fuses to an enamel.
With a blowpipe it fuses to an enamel.
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 Kurnakovite
mindat.org URL:
https://www.mindat.org/min-2295.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Kurnakovite
Reference List:
Corazza, E. (1974) The crystal structure of kurnakovite: a refinement. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 30 (9) 2194-2199 doi:10.1107/s0567740874006728
Corazza, E. (1976) Inderite: crystal structure refinement and relationship with kurnakovite. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 32 (5) 1329-1333 doi:10.1107/s0567740876005293
Jun, Li, Shuping, Xia, Shiyang, Gao (1995) FT-IR and Raman spectroscopic study of hydrated borates. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 51 (4) 519-532 doi:10.1016/0584-8539(94)00183-c
Zhou, B., Michaelis, V. K., Pan, Y., Yao, Y., Tait, K. T., Hyde, B. C., Wren, J. E. C., Sherriff, B. L., Kroeker, S. (2012) Crystal structure refinements of borate dimorphs inderite and kurnakovite using 11B and 25Mg nuclear magnetic resonance and DFT calculations. American Mineralogist, 97 (11) 1858-1865 doi:10.2138/am.2012.4020
Localities for Kurnakovite
Showing 18 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.
Argentina | |
| Helvaci +4 other references |
China | |
| Shaoxiu (1991) +2 other references |
| Xiyu Zheng (1994) | |
| Qingzhong Wang et al. (2001) |
| Xiyu Zheng and Shengsong Yu (1981) +7 other references |
| Xiyu Zheng and Shengsong Yu (1981) +1 other reference | |
| Xiyu Zheng and Shengsong Yu (1981) +3 other references | |
| Shaoxiu (1991) | |
| Wenzhi Li et al. (2004) |
Kazakhstan | |
| Pekov et al. (1993) +1 other reference |
| Godlevsky (1940) +2 other references |
Turkey | |
| Baysal (1972) +3 other references |
USA | |
| Erd et al. (1970) +2 other references |
| Rock Currier collection |
| U.S. Borax | |
| Speckels (1965) +2 other references | |
| Garrett (1998) | |
| Murdoch (1966) |
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Rio Tinto Borax Mine, Kramer Borate deposit, Boron, Kern County, California, USA