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Keldyshite

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Bratthagen 1 road cut pegmatites (Bratthagen), Lågendalen, Hedrum, Larvik, Vestfold, Norway
© OT. Ljostad 2005

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Formula:
(Na,H)
 
2
ZrSi
 
2
O
 
7
System:TriclinicColour:White
Hardness:3½ - 4½
Name:
For Mstislav Keldysh (1911-), Russian mathematician.
This page provides mineralogical data about Keldyshite.

Classification of Keldyshite

IMA status:Approved
Strunz 8th edition ID:8/C.04-10
Nickel-Strunz 10th (pending) edition ID:9.BC.10

9 : SILICATES (Germanates)
B : Sorosilicates
C : Si2O7 groups, without non-tetrahedral anions; cations in octahedral [6] and greater coordination
Dana 8th edition ID: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
Hey's CIM Ref.:14.10.6

14 : Silicates not Containing Aluminum
10 : Silicates of Zr or Hf
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Type Occurrence of Keldyshite

Type Locality:Alluaiv Mt, Lovozero Massif, Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia
Year of Discovery:1962
Geological Setting of type material:Primary mineral in foyaites.
Associated Minerals at type locality:
EudialyteLorenzenite

Physical Properties of Keldyshite

Lustre:Vitreous, Greasy
Diaphaneity (Transparency):Translucent
Colour:White
Hardness (Mohs):3½ - 4½
Hardness (Vickers):VHN100=157 - 231
Tenacity:Very brittle
Cleavage:Poor/Indistinct
Two poor cleavages intersecting at ~90 degrees.
Fracture:Irregular/Uneven
Density (measured):3.22 - 3.30 g/cm3
Density (calculated):3.26 g/cm3

Crystallography of Keldyshite

Crystal System:Triclinic
Class (H-M):1 - Pinacoidal
Space Group:P1
Cell Parameters:a = 9.01Å, b = 5.34Å, c = 6.96Å
α = 92.1°, β = 116.1°, γ = 88.1°
Ratio:a:b:c = 1.687 : 1 : 1.303
Unit Cell Volume:V 300.47 ų (Calculated from Unit Cell)
Z:2
Morphology:Irregular grains
Twinning:Very fine polysynthetic

Optical Data of Keldyshite

Type:Biaxial (-)
RI values: nα = 1.670 nγ = 1.710
2V:Measured: 78°
Maximum Birefringence:δ = 0.040

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r > v strong

Chemical Properties of Keldyshite

Formula:
(Na,H)
 
2
ZrSi
 
2
O
 
7
Essential elements:Na, O, Si, Zr
All elements listed in formula:H, Na, O, Si, Zr
Common Impurities:Ti,Fe,Ca,K

Relationship of Keldyshite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.BC.05Gittinsite
CaZr[Si
 
2
O
 
7
]
9.BC.05Keiviite-(Y)
(Y,Yb)
 
2
[Si
 
2
O
 
7
]
9.BC.05Keiviite-(Yb)
(Yb,Y)
 
2
[Si
 
2
O
 
7
]
9.BC.05Thortveitite
(Sc,Y)
 
2
[Si
 
2
O
 
7
]
9.BC.05Yttrialite-(Y)
(Y,Th)
 
2
[Si
 
2
O
 
7
]
9.BC.10Khibinskite
K
 
2
ZrSi
 
2
O
 
7
9.BC.10Parakeldyshite
Na
 
2
ZrSi
 
2
O
 
7
9.BC.15Rankinite
Ca
 
3
Si
 
2
O
 
7
9.BC.20Barysilite
Pb
 
8
Mn
2+
 
[Si
 
2
O
 
7
]
 
3
9.BC.25Edgarbaileyite
(Hg-Hg)
 
3
[Si
 
2
O
 
7
]
9.BC.30Kristiansenite
Ca
 
2
ScSn(Si
 
2
O
 
7
)(Si
 
2
O
 
6
OH)
9.BC.35Percleveite-(Ce)
(Ce,La,Nd)
 
2
[Si
 
2
O
 
7
]
Related Minerals - Hey's Index Grouping:

- +
14.10.1Zircon
Zr[SiO
 
4
]
14.10.2Hafnon
(Hf,Zr)[SiO
 
4
]
14.10.3Zektzerite
LiNa(Zr,Ti,Hf)Si
 
6
O
 
15
14.10.4Parakeldyshite
Na
 
2
ZrSi
 
2
O
 
7
14.10.5Vlasovite
Na
 
2
ZrSi
 
4
O
 
11
14.10.7Gaidonnayite
Na
 
2
Zr[Si
 
3
O
 
9
]·2H
 
2
O
14.10.8Terskite
Na
 
4
ZrSi
 
6
O
 
16
·2H
 
2
O
14.10.9Elpidite
Na
 
2
ZrSi
 
6
O
 
15
·3H
 
2
O
14.10.10Hilairite
Na
 
2
Zr[SiO
 
3
]
 
3
·3H
 
2
O
14.10.11Petarasite
Na
 
5
Zr
 
2
[(OH,Cl)|Si
 
6
O
 
18
]·2H
 
2
O
14.10.12Khibinskite
K
 
2
ZrSi
 
2
O
 
7
14.10.13Wadeite
K
 
2
Zr[Si
 
3
O
 
9
]
14.10.14Dalyite
K
 
2
ZrSi
 
6
O
 
15
14.10.15Kostylevite
K
 
2
ZrSi
 
3
O
 
9
·H
 
2
O
14.10.16Umbite
K
 
2
(Zr,Ti)Si
 
3
O
 
9
·H
 
2
O
14.10.17Paraumbite
K
 
3
Zr
 
2
H(Si
 
3
O
 
9
)
 
2
·nH
 
2
O
14.10.18Georgechaoite
NaKZr[Si
 
3
O
 
9
]·2H
 
2
O
14.10.19Gittinsite
CaZr[Si
 
2
O
 
7
]
14.10.20Calciocatapleiite
CaZrSi
 
3
O
 
9
·2H
 
2
O
14.10.21Calciohilairite
CaZr[SiO
 
3
]
 
3
·3H
 
2
O
14.10.22Armstrongite
CaZr[Si
 
6
O
 
15
]·3H
 
2
O
14.10.23Lemoynite
(Na,K)
 
2
CaZr
 
2
Si
 
10
O
 
26
·5H
 
2
O
14.10.24Catapleiite
Na
 
2
Zr[Si
 
3
O
 
9
]·2H
 
2
O
14.10.25Baghdadite
Ca
 
3
(Zr,Ti)[O
 
2
|Si
 
2
O
 
7
]
14.10.26Lovozerite
Na
 
2
Ca(Zr,Ti)[Si
 
6
O
 
12
(OH,O)
 
6
]*H
 
2
O
14.10.27Låvenite
(Na,Ca)
 
2
(Mn
2+
 
,Fe
2+
 
)(Zr,Ti)[(O,OH,F)
 
2
|Si
 
2
O
 
7
]
14.10.28Penkvilksite
Na
 
4
Ti
 
2
Si
 
8
O
 
22
·4H
 
2
O
14.10.29Darapiosite
KNa
 
2
Li(Mn,Zn)
 
2
ZrSi
 
12
O
 
30
14.10.30Bazirite
BaZr[Si
 
3
O
 
9
]
14.10.31Komkovite
BaZr[Si
 
3
O
 
9
]·3H
 
2
O
14.10.32Zirsinalite
Na
 
6
(Ca,Mn
2+
 
,Fe
2+
 
)Zr[Si
 
6
O
 
18
]
14.10.33Tranquillityite
(Fe
2+
 
,Ca)
 
8
(Zr,Y)
 
2
Ti
 
3
[O
 
4
|SiO
 
4
]
 
3

Other Names for Keldyshite

Synonyms:
IMA1975-034
Other Languages:
German:Keldyshit
Russian:Келдышит
Spanish:Keldyshita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Keldyshite

Reference List:American Mineralogist (1962): 47: 1216.

Doklady Akademii Nauk SSSR: 142: 916-918.

Trudy Mineralogicheskogo Muzeya Academii Nauk SSSR: 25: 90-95.

Doklady Akademii Nauk SSSR: 238: 573-575.

Soviet Physics – Doklady (1978): 23: 8-10.

Internet Links for Keldyshite

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    Localities for Keldyshite

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Norway
     
    • Vestfold
      • Larvik
        • Hedrum
          • Lågendalen
    		No reference listed
    Russia
     
    • Northern Region
      • Murmanskaja Oblast'
        • Kola Peninsula
          • Khibiny Massif
            • Kukisvumchorr Mt
              • East slope
                • Tuliok River head
    		P.M. Kartashov data
            • Takhtarvumchorr Mt
    		Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
          • Lovozero Massif
    		[World of Stones 95:5-6, p64]; Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    Mineral and/or Locality
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