Keiviite-(Yb)
A valid IMA mineral species
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About Keiviite-(Yb)
Formula:
Yb2Si2O7
Colour:
Colourless
Lustre:
Vitreous
Hardness:
4 - 5
Specific Gravity:
5.95
Crystal System:
Monoclinic
Member of:
Name:
Originally translated from Russian to keiviite but also appears as keivite and keivyite. The suffix was added later by the IMA to conform to the nomenclature for rare-earth-element bearing minerals. The root name is for the type locality, Keivy massif, Russia.
Unique Identifiers
Mindat ID:
2178
Long-form identifier:
mindat:1:1:2178:0
Similar Names
| Keiviite-(Y) | A valid IMA mineral species | Y2Si2O7 |
| Keiviite-(Y)-Keiviite-(Yb) Series | A solid-solution series between two end-member minerals | |
| Kievite | A synonym of Cummingtonite | |
| Kivite | A rock subtype | |
| Kivuite | A discredited species name | Th(UO2)4(PO3OH)2(OH)8 · 7H2O |
IMA Classification of Keiviite-(Yb)
Approved
IMA status notes:
Renamed by the IMA
IMA Formula:
Yb3+2Si2O7
Approval year:
1982
First published:
1983
Classification of Keiviite-(Yb)
9.BC.05
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
55.2.1a.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
14.8.3
14 : Silicates not Containing Aluminum
8 : Silicates of Group III metals other than Al
14 : Silicates not Containing Aluminum
8 : Silicates of Group III metals other than Al
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 |
|---|---|---|
| Kvi-Yb | 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 Keiviite-(Yb)
Vitreous
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Hardness:
4 - 5 on Mohs scale
Cleavage:
Perfect
perfect on {110}, imperfect on {001}
perfect on {110}, imperfect on {001}
Density:
5.95 g/cm3 (Measured) 5.99 g/cm3 (Calculated)
Optical Data of Keiviite-(Yb)
Type:
Biaxial (-)
RI values:
nα = 1.723 nβ = 1.758 nγ = 1.768
2V:
Measured: 58°
Max. Birefringence:
δ = 0.045
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
Optical Extinction:
Z = b; X ∧ c = 3°-5°; Y ∧ a = 7°-8°.
Chemistry of Keiviite-(Yb)
Mindat Formula:
Yb2Si2O7
Element Weights:
Elements listed:
Crystallography of Keiviite-(Yb)
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 6.840(2) Å, b = 8.916(2) Å, c = 4.745(1) Å
β = 102.11(3)°
β = 102.11(3)°
Ratio:
a:b:c = 0.767 : 1 : 0.532
Unit Cell V:
282.94 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Elongated platy and prismatic crystals.
Twinning:
Polysynthetic - common.
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) |
|---|---|---|---|---|---|---|---|
| 0015614 | Keiviite-(Yb) | Yakubovich O V, Simonov M A, Voloshin A V, Pakhomovsky Y A (1986) Crystal structure of keivite Yb2[Si2O7] Soviet Physics Doklady 31 930-932 | 1986 | Kola Peninsula, Russia | 0 | 293 | |
| 0009370 | Keiviite-(Yb) | Smolin Y I, Shepelev Y F (1970) The crystal structures of the rare earth pyrosilicates Acta Crystallographica B26 484-492 |  | 1970 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.24 Å | (100) |
| 3.20 Å | (100) |
| 3.03 Å | (90) |
| 4.64 Å | (80) |
| 2.720 Å | (70) |
| 2.674 Å | (70) |
| 2.262 Å | (70) |
| 2.165 Å | (60) |
| 2.127 Å | (60b) |
| 1.692 Å | (60) |
| 5.36 Å | (50) |
| 1.920 Å | (50) |
| 1.578 Å | (50) |
Comments:
Mt. Ploskaya, Russia. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Keiviite-(Yb)
General Appearance of Type Material:
Single crystals and intergrowths 0.1-0.8 mm.
Place of Conservation of Type Material:
A.E. Fersman Museum, Moscow, Russia.
Geological Setting of Type Material:
Microcline bearing pegmatites.
Associated Minerals at Type Locality:
Synonyms of Keiviite-(Yb)
Other Language Names for Keiviite-(Yb)
Relationship of Keiviite-(Yb) to other Species
Member of:
Other Members of Thortveitite Group:
| Keiviite-(Y) | Y2Si2O7 | Mon. 2/m : B2/m |
| Thortveitite | Sc2Si2O7 | Mon. 2/m : B2/m |
| Yttrialite-(Y) | (Y,Th)2Si2O7 | Mon. 2/m : P21/m |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 6 photos of Keiviite-(Yb) associated with 'Yttrofluorite' | (Ca1-xYx)F2+x where 0.05 < x < 0.3 |
| 2 photos of Keiviite-(Yb) associated with Fluorite | CaF2 |
| 1 photo of Keiviite-(Yb) associated with 'Amazonite' | K(AlSi3O8) |
| 1 photo of Keiviite-(Yb) associated with Monazite-(Ce) | Ce(PO4) |
| 1 photo of Keiviite-(Yb) associated with 'Zinnwaldite' |
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 | Gittinsite | CaZrSi2O7 |
| 9.BC.10 | Parakeldyshite | Na2ZrSi2O7 |
| 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 Keiviite-(Yb)
Faint green cathodoluminescence.
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 Keiviite-(Yb)
mindat.org URL:
https://www.mindat.org/min-2178.html
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References for Keiviite-(Yb)
Reference List:
Dunn, Pete J.; Cabri, Louis J.; Ferraiolo, James A.; Grice, Joel Do.; Jambor, John L.; Mueller, Wolfgang; Shigley, James E.; Puziewicz, Jacek; Vanko, David A. (1984) New mineral names. American Mineralogist, 69 (11-12). 1190-1196
Nickel, Ernest H., Mandarino, Joseph A. (1987) Procedures involving the IMA Commission on New Minerals and Mineral Names and guidelines on mineral nomenclature. American Mineralogist, 72 (9-10) 1031-1042 (as keivyite)
Christensen, A. Nørlund, Hazell, R. G., Hewat, A. W., Fondo, Matilde, Gómez-Fórneas, Esther, McAuliffe, Charles A., Styring, Stenbjörn, Tommos, Cecilia, Warncke, Kurt, Wood, Bryan R. (1997) Synthesis, Crystal Growth and Structure Investigations of Rare-Earth Disilicates and Rare-Earth Oxyapatites. Acta Chemica Scandinavica, 51. 37-43 doi:10.3891/acta.chem.scand.51-0037
Localities for Keiviite-(Yb)
Showing 2 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.
Norway | |
| Husdal (2008) |
Russia (TL) | |
| Voloshin A.V. et al. (1983) +2 other references |
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Ploskaya Mountain, Western Keivy Massif, Keivy Mountains, Lovozersky District, Murmansk Oblast, Russia