Crystal chemistry of neptunite from the Khan Bogdo alkaline massif (Mongolia)

A. A. Zolotarev, N. V. Vladykin, S. V. Krivovichev, T. L. Panikorovskii

Research output

Abstract

Crystal chemical characteristics have been studied for neptunite from alkaline granites of the Khan Bogdo massif (Southern Mongolia). The mineral occurs to be the practically clear Fe-variety of its species. Refinement of its crystal structure was carried out in two space groups: centric C2/c and acentric Cc. It is indicated that correct space group is the acentric Cc due to ordering of octahedral cations Ti and Fe. The structure was refined to R 1 = 0.025 (wR 2 = 0.057) for 4889 reflections with |Fo| ≥ 4σF. Unit cell parameters: a = 16.4542(7), b = 12.5115(4), c = 9.9980(4) Å, β = 115.542(5)°, V = 1857.10(15) Å 3 , Z = 4. Ti octahedra show strong distortions: one bond Ti-O 1.75 Å, another bond 2.20 Å, and four Ti-O bonds around 2.0 Å. Fe octahedra have a more regular shape with an average bond length Fe-O 2.13-2.14 Å. Empirical formula calculated on the basis of chemical analysis is (K 0.86 Cs 0.02 Zn 0.02 Ca 0.01 ) S0.91 Na 1.90 Li 0.82 (Fe 1.54 2+ Fe 0.22 3+ Mn 0.16 Mn 0.04 ) S1.96 Ti 2.1 (Si 7.76 Al 0.25 )O 24 . Structural formula is K 0.97 Na 1.90 (Li 0.94 Na 0.06 ) S1.00 (Fe 1.80 Mn 0.15 Mg 0.05 ) S2.00 Ti 2 Si 8 O 22 (O,OH) 2 . Idealized formula is KNa 2 LiFe 2 Ti 2 Si 8 O 24

Original languageEnglish
Pages (from-to)112-127
Number of pages16
JournalZapiski Rossiiskogo Mineralogicheskogo Obshchestva
Volume145
Issue number2
Publication statusPublished - 1 Jan 2016

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Crystal chemistry
crystal chemistry
Bond length
Minerals
Cations
Crystal structure
Positive ions
Crystals
Chemical analysis
crystal structure
chemical analysis
cation
crystal
mineral
chemical
parameter

Scopus subject areas

  • Geochemistry and Petrology
  • Geology
  • Economic Geology
  • Materials Chemistry

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@article{2a05dc93529744a098e8790785239de3,
title = "Crystal chemistry of neptunite from the Khan Bogdo alkaline massif (Mongolia)",
abstract = "Crystal chemical characteristics have been studied for neptunite from alkaline granites of the Khan Bogdo massif (Southern Mongolia). The mineral occurs to be the practically clear Fe-variety of its species. Refinement of its crystal structure was carried out in two space groups: centric C2/c and acentric Cc. It is indicated that correct space group is the acentric Cc due to ordering of octahedral cations Ti and Fe. The structure was refined to R 1 = 0.025 (wR 2 = 0.057) for 4889 reflections with |Fo| ≥ 4σF. Unit cell parameters: a = 16.4542(7), b = 12.5115(4), c = 9.9980(4) {\AA}, β = 115.542(5)°, V = 1857.10(15) {\AA} 3 , Z = 4. Ti octahedra show strong distortions: one bond Ti-O 1.75 {\AA}, another bond 2.20 {\AA}, and four Ti-O bonds around 2.0 {\AA}. Fe octahedra have a more regular shape with an average bond length Fe-O 2.13-2.14 {\AA}. Empirical formula calculated on the basis of chemical analysis is (K 0.86 Cs 0.02 Zn 0.02 Ca 0.01 ) S0.91 Na 1.90 Li 0.82 (Fe 1.54 2+ Fe 0.22 3+ Mn 0.16 Mn 0.04 ) S1.96 Ti 2.1 (Si 7.76 Al 0.25 )O 24 . Structural formula is K 0.97 Na 1.90 (Li 0.94 Na 0.06 ) S1.00 (Fe 1.80 Mn 0.15 Mg 0.05 ) S2.00 Ti 2 Si 8 O 22 (O,OH) 2 . Idealized formula is KNa 2 LiFe 2 Ti 2 Si 8 O 24",
keywords = "Equivalent and anisotropic displacement parameters, Fe-dominant neptunite, Inter-atomic distances, Mangan-neptunite, Pyroxene type and octahedral chains, Refined crystal structure",
author = "Zolotarev, {A. A.} and Vladykin, {N. V.} and Krivovichev, {S. V.} and Panikorovskii, {T. L.}",
year = "2016",
month = "1",
day = "1",
language = "English",
volume = "145",
pages = "112--127",
journal = "ЗАПИСКИ РОССИЙСКОГО МИНЕРАЛОГИЧЕСКОГО ОБЩЕСТВА",
issn = "0869-6055",
publisher = "Издательство {"}Наука{"}",
number = "2",

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TY - JOUR

T1 - Crystal chemistry of neptunite from the Khan Bogdo alkaline massif (Mongolia)

AU - Zolotarev, A. A.

AU - Vladykin, N. V.

AU - Krivovichev, S. V.

AU - Panikorovskii, T. L.

PY - 2016/1/1

Y1 - 2016/1/1

N2 - Crystal chemical characteristics have been studied for neptunite from alkaline granites of the Khan Bogdo massif (Southern Mongolia). The mineral occurs to be the practically clear Fe-variety of its species. Refinement of its crystal structure was carried out in two space groups: centric C2/c and acentric Cc. It is indicated that correct space group is the acentric Cc due to ordering of octahedral cations Ti and Fe. The structure was refined to R 1 = 0.025 (wR 2 = 0.057) for 4889 reflections with |Fo| ≥ 4σF. Unit cell parameters: a = 16.4542(7), b = 12.5115(4), c = 9.9980(4) Å, β = 115.542(5)°, V = 1857.10(15) Å 3 , Z = 4. Ti octahedra show strong distortions: one bond Ti-O 1.75 Å, another bond 2.20 Å, and four Ti-O bonds around 2.0 Å. Fe octahedra have a more regular shape with an average bond length Fe-O 2.13-2.14 Å. Empirical formula calculated on the basis of chemical analysis is (K 0.86 Cs 0.02 Zn 0.02 Ca 0.01 ) S0.91 Na 1.90 Li 0.82 (Fe 1.54 2+ Fe 0.22 3+ Mn 0.16 Mn 0.04 ) S1.96 Ti 2.1 (Si 7.76 Al 0.25 )O 24 . Structural formula is K 0.97 Na 1.90 (Li 0.94 Na 0.06 ) S1.00 (Fe 1.80 Mn 0.15 Mg 0.05 ) S2.00 Ti 2 Si 8 O 22 (O,OH) 2 . Idealized formula is KNa 2 LiFe 2 Ti 2 Si 8 O 24

AB - Crystal chemical characteristics have been studied for neptunite from alkaline granites of the Khan Bogdo massif (Southern Mongolia). The mineral occurs to be the practically clear Fe-variety of its species. Refinement of its crystal structure was carried out in two space groups: centric C2/c and acentric Cc. It is indicated that correct space group is the acentric Cc due to ordering of octahedral cations Ti and Fe. The structure was refined to R 1 = 0.025 (wR 2 = 0.057) for 4889 reflections with |Fo| ≥ 4σF. Unit cell parameters: a = 16.4542(7), b = 12.5115(4), c = 9.9980(4) Å, β = 115.542(5)°, V = 1857.10(15) Å 3 , Z = 4. Ti octahedra show strong distortions: one bond Ti-O 1.75 Å, another bond 2.20 Å, and four Ti-O bonds around 2.0 Å. Fe octahedra have a more regular shape with an average bond length Fe-O 2.13-2.14 Å. Empirical formula calculated on the basis of chemical analysis is (K 0.86 Cs 0.02 Zn 0.02 Ca 0.01 ) S0.91 Na 1.90 Li 0.82 (Fe 1.54 2+ Fe 0.22 3+ Mn 0.16 Mn 0.04 ) S1.96 Ti 2.1 (Si 7.76 Al 0.25 )O 24 . Structural formula is K 0.97 Na 1.90 (Li 0.94 Na 0.06 ) S1.00 (Fe 1.80 Mn 0.15 Mg 0.05 ) S2.00 Ti 2 Si 8 O 22 (O,OH) 2 . Idealized formula is KNa 2 LiFe 2 Ti 2 Si 8 O 24

KW - Equivalent and anisotropic displacement parameters

KW - Fe-dominant neptunite

KW - Inter-atomic distances

KW - Mangan-neptunite

KW - Pyroxene type and octahedral chains

KW - Refined crystal structure

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JO - ЗАПИСКИ РОССИЙСКОГО МИНЕРАЛОГИЧЕСКОГО ОБЩЕСТВА

JF - ЗАПИСКИ РОССИЙСКОГО МИНЕРАЛОГИЧЕСКОГО ОБЩЕСТВА

SN - 0869-6055

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