Keldyshite
A valid IMA mineral species
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About Keldyshite
Mstislav Keldysh
Formula:
(Na,H)2ZrSi2O7
Colour:
White
Lustre:
Vitreous, Greasy
Hardness:
3½ - 4½
Specific Gravity:
3.22 - 3.30
Crystal System:
Triclinic
Name:
Named in 1962 by Vasilii Ivanovich Gerasimovsky in honor of Mstislav Vsevolodovich Keldysh [February 10 (old calendar January 28), 1911 Riga, Russia - June 24, 1978], Russian mathematician and father of the first Earth space program. Keldysh proposed and developed the first orbiting satellite, Sputnik, and was given the epithet "Chief Theoretician" by his colleagues in the Russian Space Program.
This page provides mineralogical data about Keldyshite.
Unique Identifiers
Mindat ID:
2179
Long-form identifier:
mindat:1:1:2179:7
IMA Classification of Keldyshite
Classification of Keldyshite
9.BC.10
9 : SILICATES (Germanates)
B : Sorosilicates
C : Si2O7 groups, without non-tetrahedral anions; cations in octahedral [6] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
C : Si2O7 groups, without non-tetrahedral anions; cations in octahedral [6] and greater coordination
55.2.2.1
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
2 : Si2O7 Groups, Generally with no Additional Anions with cations in [6] coordination
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
2 : Si2O7 Groups, Generally with no Additional Anions with cations in [6] coordination
14.10.6
14 : Silicates not Containing Aluminum
10 : Silicates of Zr or Hf
14 : Silicates not Containing Aluminum
10 : Silicates of Zr or Hf
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 |
|---|---|---|
| Kel | 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 Keldyshite
Vitreous, Greasy
Transparency:
Translucent
Colour:
White
Streak:
White
Hardness:
3½ - 4½ on Mohs scale
Hardness:
VHN100=157 - 231 - Vickers
Tenacity:
Very brittle
Cleavage:
Poor/Indistinct
Two poor cleavages intersecting at ~90 degrees.
Two poor cleavages intersecting at ~90 degrees.
Fracture:
Irregular/Uneven
Density:
3.22 - 3.30 g/cm3 (Measured) 3.26 g/cm3 (Calculated)
Optical Data of Keldyshite
Type:
Biaxial (-)
RI values:
nα = 1.67 nγ = 1.71
2V:
Measured: 78°
Max. Birefringence:
δ = 0.040
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
Dispersion:
r > v strong
Chemistry of Keldyshite
Mindat Formula:
(Na,H)2ZrSi2O7
Element Weights:
Common Impurities:
Ti,Fe,Ca,K
Crystallography of Keldyshite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 9.01 Å, b = 5.34 Å, c = 6.96 Å
α = 92.1°, β = 116.1°, γ = 88.1°
α = 92.1°, β = 116.1°, γ = 88.1°
Ratio:
a:b:c = 1.687 : 1 : 1.303
Unit Cell V:
300.47 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Irregular grains
Twinning:
Very fine polysynthetic
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) |
|---|---|---|---|---|---|---|---|
| 0012457 | Keldyshite | Khalikov A D, Khomyakov A P, Makhmudov S A (1978) Crystal structure of keldyshite NaZr[Si2O6OH] Doklady Akademii Nauk SSSR 238 573-575 | 1978 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.97 Å | (100) |
| 4.11 Å | (70) |
| 1.542 Å | (70) |
| 1.097 Å | (60) |
| 1.013 Å | (60) |
| 2.95 Å | (50) |
| 2.66 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Keldyshite
General Appearance of Type Material:
Irregular grains up to 4 mm in size and as aggregates up to 6 mm.
Place of Conservation of Type Material:
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 64710, 64711.
Geological Setting of Type Material:
Primary mineral in foyaites.
Associated Minerals at Type Locality:
Synonyms of Keldyshite
Other Language Names for Keldyshite
Common Associates
Associations Based on Photo Data:
| 20 photos of Keldyshite associated with Parakeldyshite | Na2ZrSi2O7 |
| 10 photos of Keldyshite associated with Aegirine | NaFe3+Si2O6 |
| 3 photos of Keldyshite associated with Eudialyte | Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2 |
| 3 photos of Keldyshite associated with Feldspar Group | |
| 3 photos of Keldyshite associated with Nepheline | Na3K(Al4Si4O16) |
| 2 photos of Keldyshite associated with Ferrokentbrooksite | Na15Ca6(Fe,Mn)3Zr3NbSi25O73(O,OH,H2O)3Cl2 |
| 2 photos of Keldyshite associated with Albite | Na(AlSi3O8) |
| 1 photo of Keldyshite associated with Catapleiite | Na2Zr(Si3O9) · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 9.BC. | Anorthoyttrialite-(Y) | Y4(SiO4)(Si3O10) |
| 9.BC. | Kozłowskiite | Ca4(Fe2+Sn3)[Si2O7]2[Si2O6OH]2 |
| 9.BC.05 | Yttrialite-(Y) | (Y,Th)2Si2O7 |
| 9.BC.05 | Thortveitite | Sc2Si2O7 |
| 9.BC.05 | Keiviite-(Y) | Y2Si2O7 |
| 9.BC.05 | Keiviite-(Yb) | Yb2Si2O7 |
| 9.BC.05 | Gittinsite | CaZrSi2O7 |
| 9.BC.10 | Parakeldyshite | Na2ZrSi2O7 |
| 9.BC.10 | Khibinskite | K2ZrSi2O7 |
| 9.BC.10 | Brunovskyite | NaZrSi2O6(OH) |
| 9.BC.15 | Rankinite | Ca3Si2O7 |
| 9.BC.20 | Barysilite | Pb8Mn2+[Si2O7]3 |
| 9.BC.25 | Edgarbaileyite | [Hg2]2+3[Si2O7] |
| 9.BC.30 | Kristiansenite | Ca4(Sc2Sn2)[Si2O7]2[Si2O6OH]2 |
| 9.BC.30 | Nybergite | Ca4Sc3Sn(Si2O7)(Si2O6OH)3 |
| 9.BC.30 | Silesiaite | Ca4(Fe3+2Sn2)[Si2O7]2[Si2O6OH]2 |
| 9.BC.35 | Percleveite-(Ce) | Ce2Si2O7 |
| 9.BC.35 | Percleveite-(La) | La2Si2O7 |
| 9.BC.40 | Scottyite | BaCu2Si2O7 |
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 Keldyshite
mindat.org URL:
https://www.mindat.org/min-2179.html
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References for Keldyshite
Localities for Keldyshite
Showing 12 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.
Libya | |
| Flinn et al (1992) |
| Flinn et al. (1992) | |
Morocco | |
| Bea et al. (2013) |
Norway | |
| Larsen et al. (2010) |
Russia | |
| Pavel M. Kartashov (n.d.) |
| [World of Stones 95:5-6 +2 other references |
| Pavel M. Kartashov (n.d.) | |
| Pekov (1998) | |
| Petrovsky et al. (2012) | |
| Pekov (1998) | |
| Arzamastsev et al. (2008) |
| Pekov (1998) |
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