Parakeldyshite
A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
About Parakeldyshite
Formula:
Na2ZrSi2O7
Colour:
White, pale blue
Lustre:
Vitreous
Hardness:
5½ - 6
Specific Gravity:
3.37 - 3.39
Crystal System:
Triclinic
Name:
Named for its chemical relationship to keldyshite.
This page provides mineralogical data about Parakeldyshite.
Unique Identifiers
Mindat ID:
3094
Long-form identifier:
mindat:1:1:3094:2
IMA Classification of Parakeldyshite
Approved
IMA Formula:
Na2Zr4+Si2O7
Approval year:
1975
First published:
1977
Classification of Parakeldyshite
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
55.2.2.3
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
14.10.4
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 |
|---|---|---|
| Pkel | 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 Parakeldyshite
Vitreous
Colour:
White, pale blue
Hardness:
5½ - 6 on Mohs scale
Cleavage:
Perfect
Three cleavages result in a pseudo-rhombohedral shape: {001} perfect, {110} and {110} somewhat less perfect. The acute angles between these planes are all between 76° and 82°. Also a good cleavage parallel to {011}.
Three cleavages result in a pseudo-rhombohedral shape: {001} perfect, {110} and {110} somewhat less perfect. The acute angles between these planes are all between 76° and 82°. Also a good cleavage parallel to {011}.
Density:
3.37 - 3.39 g/cm3 (Measured) 3.40 g/cm3 (Calculated)
Optical Data of Parakeldyshite
Type:
Biaxial (-)
RI values:
nα = 1.670 nβ = 1.692 - 1.697 nγ = 1.713 - 1.718
2V:
Measured: 83° to 84°, Calculated: 88°
Max. Birefringence:
δ = 0.043 - 0.048
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:
Very High (positive)
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 strong
Optical Extinction:
Y ≈ c; X ≈ b; Z ≈ a.
Chemistry of Parakeldyshite
Mindat Formula:
Na2ZrSi2O7
Element Weights:
Elements listed:
Common Impurities:
Ti,Hf,Al,Fe,Mg,Ca,K,H2O
Crystallography of Parakeldyshite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 5.419(1) Å, b = 6.607(2) Å, c = 8.806(2) Å
α = 71.50(2)°, β = 87.15(3)°, γ = 85.63(2)°
α = 71.50(2)°, β = 87.15(3)°, γ = 85.63(2)°
Ratio:
a:b:c = 0.82 : 1 : 1.333
Unit Cell V:
298.01 ų (Calculated from Unit Cell)
Z:
2
Twinning:
Polysynthetic on {100}, with several other sets intersecting.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0018674 | Parakeldyshite | Pekov I V, Zubkova N V, Pushcharovsky D Y, Kolitsch U, Tillmanns E (2007) Refined crystal structure of parakeldyshite and genetic crystal chemistry of zirconium minerals with [Si2O7] diorthogroups Crystallography Reports 52 1066-1071 | 2007 | Alluaiv Mountain (Lovozero), Kola Peninsula, Russia | 0 | 293 | |
| 0014056 | Parakeldyshite | Voronkov A A, Shumyatskaya N G, Pyatenko Y A (1970) Crystal structure of a new natural modification of Na2Zr[Si2O7] Journal of Structural Chemistry 11 866-867 | 1970 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.963 Å | (10) |
| 2.913 Å | (9) |
| 4.234 Å | (7) |
| 2.703 Å | (7) |
| 6.00 Å | (6) |
| 2.718 Å | (6) |
| 2.905 Å | (5) |
Comments:
Bratthagen, Norway. Data from Raade and Mladeck (1977).
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 Parakeldyshite
Co-Type Localities:
General Appearance of Type Material:
Grains to 5 mm and aggregates.
Place of Conservation of Type Material:
Geology Museum, Kola Branch, Academy of Sciences, Apatity, 3270, 4457; Mining Institute, St. Petersburg, 1079/1{2, vis4361; Vernadsky Geological Museum, Moscow, 517151; A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 78461, 78462
Associated Minerals at Type Locality:
Synonyms of Parakeldyshite
Other Language Names for Parakeldyshite
Common Associates
Associations Based on Photo Data:
| 20 photos of Parakeldyshite associated with Keldyshite | (Na,H)2ZrSi2O7 |
| 9 photos of Parakeldyshite associated with Aegirine | NaFe3+Si2O6 |
| 8 photos of Parakeldyshite associated with Sodalite | Na4(Si3Al3)O12Cl |
| 8 photos of Parakeldyshite associated with Kentbrooksite | (Na,REE)15(Ca,REE)6(Mn2+,Fe2+)3Zr3Nb[Si25O74]F2 · 2H2O |
| 4 photos of Parakeldyshite associated with Albite | Na(AlSi3O8) |
| 2 photos of Parakeldyshite associated with Nepheline | Na3K(Al4Si4O16) |
| 1 photo of Parakeldyshite associated with Catapleiite | Na2Zr(Si3O9) · 2H2O |
| 1 photo of Parakeldyshite associated with Eudialyte | Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2 |
| 1 photo of Parakeldyshite associated with Lorenzenite | Na2Ti2(Si2O6)O3 |
| 1 photo of Parakeldyshite associated with Loparite | (Na,REE)2Ti2O6 |
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 | Keldyshite | (Na,H)2ZrSi2O7 |
| 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 |
Fluorescence of Parakeldyshite
Fluoresces deep cream under SW UV and a very weak cream under LW UV.
Other Information
Special Storage/
Display Requirements:
Display Requirements:
Alters readily to a snow-white coating.
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 Parakeldyshite
mindat.org URL:
https://www.mindat.org/min-3094.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 Parakeldyshite
Localities for Parakeldyshite
Showing 17 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 (1989) +1 other reference |
Germany | |
| Juroszek et al. (Ti 5 Fe) |
| Skrzyńska et al. (2023) | |
Norway | |
| Raade et al. (1977) |
Russia | |
| Pavel M. Kartashov (n.d.) |
| Pekov (2003) |
| Pavel M. Kartashov (n.d.) | |
| Pakhomovsky et al. (2014) | |
| Petrovsky et al. (2012) | |
| Pekov (1998) | |
| Yakovenchuk et al. (2019) | |
| Arzamastsev et al. (2008) | |
| Pekov (1998) |
| Pekov (1998) |
South Africa | |
| Kamenetsky et al. (2014) |
| R. Liferovich -L. Horváth p.c. 2004 |
USA | |
| Prof. W. Stoll (pers. comm. 2004) +8 other references |
Quick NavTopAbout ParakeldyshiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Bratthagen 1, Lågendalen, Hedrum, Larvik Commune, Vestfold, Norway