Parakeldyshite
A valid IMA mineral species
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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
GUID
(UUID V4):
(UUID V4):
3a05b080-b06f-4448-bcdc-edf3b65b2d6e
IMA Classification of Parakeldyshite
Approved
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 |
|---|---|---|
| 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
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v strong
Optical Extinction:
Y ≈ c; X ≈ b; Z ≈ a.
Chemistry of Parakeldyshite
Mindat Formula:
Na2ZrSi2O7
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
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 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:
Reference:
Sizova R G, Kuz'min E A, Ilyukhin V V (1975) Deciphering the continuous Patterson function of the Na,Zr-diorthosilicate Na2ZrSi2O7 (parakeldyshite) by the vector subsystem method. Konstitutsiya i Svoistva Mineralov 9, 10-12
Synonyms of Parakeldyshite
Other Language Names for Parakeldyshite
Common Associates
Associated Minerals Based on Photo Data:
| 18 photos of Parakeldyshite associated with Keldyshite | (Na,H)2ZrSi2O7 |
| 8 photos of Parakeldyshite associated with Aegirine | NaFe3+Si2O6 |
| 8 photos of Parakeldyshite associated with Kentbrooksite | (Na,REE)15(Ca,REE)6(Mn2+,Fe2+)3Zr3Nb[Si25O74]F2 · 2H2O |
| 5 photos of Parakeldyshite associated with Sodalite | Na4(Si3Al3)O12Cl |
| 4 photos of Parakeldyshite associated with Albite | Na(AlSi3O8) |
| 2 photos of Parakeldyshite associated with Nepheline | Na3K(Al4Si4O16) |
| 1 photo of Parakeldyshite associated with Lorenzenite | Na2Ti2(Si2O6)O3 |
| 1 photo of Parakeldyshite associated with Loparite-(Ce) | (Na,REE)2Ti2O6 |
| 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 |
Related Minerals - Strunz-mindat Grouping
| 9.BC. | Kozłowskiite | Ca4Fe2+2Sn3(Si2O7)2(Si2O6OH)2 |
| 9.BC. | Anorthoyttrialite-(Y) | Y4(SiO4)(Si3O10) |
| 9.BC.05 | Gittinsite | CaZrSi2O7 |
| 9.BC.05 | Keiviite-(Y) | Y2Si2O7 |
| 9.BC.05 | Keiviite-(Yb) | Yb2Si2O7 |
| 9.BC.05 | Thortveitite | Sc2Si2O7 |
| 9.BC.05 | Yttrialite-(Y) | (Y,Th)2Si2O7 |
| 9.BC.10 | Keldyshite | (Na,H)2ZrSi2O7 |
| 9.BC.10 | Khibinskite | K2ZrSi2O7 |
| 9.BC.15 | Rankinite | Ca3Si2O7 |
| 9.BC.20 | Barysilite | Pb8Mn2+[Si2O7]3 |
| 9.BC.25 | Edgarbaileyite | [Hg2]2+3[Si2O7] |
| 9.BC.30 | Kristiansenite | Ca4Sc2Sn2(Si2O7)2(Si2O6OH)2 |
| 9.BC.30 | Silesiaite | Ca4Fe3+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
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References for Parakeldyshite
Localities for Parakeldyshite
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 | |
| 166-175. +2 other references |
Germany | |
| Skrzyńska et al. (2023) |
Norway | |
| Raade et al. (1977) |
Russia | |
| Pavel.M. Kartashov (n.d.) |
| Yakovenchuk et al. (2019) | |
| Arzamastsev et al. (2008) | |
| Pekov (1998) |
| Pekov (1998) |
| Pekov (2003) |
| Pavel.M. Kartashov (n.d.) | |
| Pakhomovsky et al. (2014) | |
| Petrovsky et al. (2012) | |
| 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 |
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Bratthagen 1, Lågendalen, Hedrum, Larvik, Vestfold, Norway