Trigonal variation in the garnet supergroup

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Trigonal variation in the garnet supergroup : The crystal structure of nikmelnikovite, Ca₁₂Fe²⁺Fe³⁺₃Al₃(SiO₄)₆(OH)₂₀, from Kovdor massif, Kola Peninsula, Russia. / Krivovichev, Sergey V.; Panikorovskii, Taras L.; Yakovenchuk, Victor N.; Selivanova, Ekaterina A.; Ivanyuk, Gregory Yu.

In: Mineralogical Magazine, Vol. 85, No. 4, 08.2021, p. 620-626.

Research output: Contribution to journal › Article › peer-review

Author

Krivovichev, Sergey V. ; Panikorovskii, Taras L. ; Yakovenchuk, Victor N. ; Selivanova, Ekaterina A. ; Ivanyuk, Gregory Yu. / Trigonal variation in the garnet supergroup : The crystal structure of nikmelnikovite, Ca₁₂Fe²⁺Fe³⁺₃Al₃(SiO₄)₆(OH)₂₀, from Kovdor massif, Kola Peninsula, Russia. In: Mineralogical Magazine. 2021 ; Vol. 85, No. 4. pp. 620-626.

BibTeX

@article{2c92ed0aeca44a51b94d0fad97c8992b,

title = "Trigonal variation in the garnet supergroup: The crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, from Kovdor massif, Kola Peninsula, Russia",

abstract = "The crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, a new member of the garnet supergroup from Kovdor massif, Kola Peninsula, Russia (R, a = 17.2072(6), c = 10.5689(4) {\AA}, V = 2710.1(2) {\AA}3 and Z = 3) has been refined to R1 = 0.046 on the basis of 1184 unique observed reflections. Nikmelnikovite is the first mineral species in the garnet supergroup that has a trigonal (rhombohedral) symmetry. The relationship between its unit cell and the pseudocubic (ideal garnet) unit cell can be described by the transformation matrix [10 | 01 | ½½½]. The crystal-chemical relations between the ideal Iad garnet and the nikmelnikovite structure type can be described by the following series of imaginary modifications: (1) the symmetry is lowered according to the Iad → R group-subgroup relationship; (2) the cation sites are split according to the following sequences: X → {X1, X2}; Y → {Y1, Y2, Y3, Y4}; Z → {Z1, Z2}; (3) the X sites remain fully occupied by Ca; (4) each Y site is occupied predominantly by a distinct chemical species: Y1 → Al (Al site), Y2 → Fe2+ (Fe1 site), Y3 → Fe3+ (Fe2 site), Y4 → vacancy (Mn site); (5) one of the Z sites (Z1) is occupied by Si, whereas the other site (Z2) is predominantly vacant. The crystal-chemical formula that takes into account the transition between the archetype and the nikmelnikovite structure type can be described as X{Ca12}Y[Fe2+Al4Fe3+2□]Z(Si6□6)O24(OH)20□4. The structural complexity of nikmelnikovite (4.529 bit/atom and 434.431 bit/cell, after H-correction) is higher than those for andradite, grossular and katoite, which is typical for low-temperature minerals formed after primary minerals with simpler structures.",

keywords = "crystal structure, garnet, Kola peninsula, Kovdor, nikmelnikovite, Russian Arctic, COMPLEXITY, OH, DISSYMMETRIZATION",

author = "Krivovichev, {Sergey V.} and Panikorovskii, {Taras L.} and Yakovenchuk, {Victor N.} and Selivanova, {Ekaterina A.} and Ivanyuk, {Gregory Yu}",

note = "Publisher Copyright: Copyright {\textcopyright} The Author(s), 2021. Published by Cambridge University Press on behalf of The Mineralogical Society of Great Britain and Ireland.",

year = "2021",

month = aug,

doi = "10.1180/mgm.2021.55",

language = "English",

volume = "85",

pages = "620--626",

journal = "Mineralogical Magazine",

issn = "0026-461X",

publisher = "Mineralogical Society",

number = "4",

}

RIS

TY - JOUR

T1 - Trigonal variation in the garnet supergroup

T2 - The crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, from Kovdor massif, Kola Peninsula, Russia

AU - Krivovichev, Sergey V.

AU - Panikorovskii, Taras L.

AU - Yakovenchuk, Victor N.

AU - Selivanova, Ekaterina A.

AU - Ivanyuk, Gregory Yu

PY - 2021/8

Y1 - 2021/8

N2 - The crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, a new member of the garnet supergroup from Kovdor massif, Kola Peninsula, Russia (R, a = 17.2072(6), c = 10.5689(4) Å, V = 2710.1(2) Å3 and Z = 3) has been refined to R1 = 0.046 on the basis of 1184 unique observed reflections. Nikmelnikovite is the first mineral species in the garnet supergroup that has a trigonal (rhombohedral) symmetry. The relationship between its unit cell and the pseudocubic (ideal garnet) unit cell can be described by the transformation matrix [10 | 01 | ½½½]. The crystal-chemical relations between the ideal Iad garnet and the nikmelnikovite structure type can be described by the following series of imaginary modifications: (1) the symmetry is lowered according to the Iad → R group-subgroup relationship; (2) the cation sites are split according to the following sequences: X → {X1, X2}; Y → {Y1, Y2, Y3, Y4}; Z → {Z1, Z2}; (3) the X sites remain fully occupied by Ca; (4) each Y site is occupied predominantly by a distinct chemical species: Y1 → Al (Al site), Y2 → Fe2+ (Fe1 site), Y3 → Fe3+ (Fe2 site), Y4 → vacancy (Mn site); (5) one of the Z sites (Z1) is occupied by Si, whereas the other site (Z2) is predominantly vacant. The crystal-chemical formula that takes into account the transition between the archetype and the nikmelnikovite structure type can be described as X{Ca12}Y[Fe2+Al4Fe3+2□]Z(Si6□6)O24(OH)20□4. The structural complexity of nikmelnikovite (4.529 bit/atom and 434.431 bit/cell, after H-correction) is higher than those for andradite, grossular and katoite, which is typical for low-temperature minerals formed after primary minerals with simpler structures.

AB - The crystal structure of nikmelnikovite, Ca12Fe2+Fe3+3Al3(SiO4)6(OH)20, a new member of the garnet supergroup from Kovdor massif, Kola Peninsula, Russia (R, a = 17.2072(6), c = 10.5689(4) Å, V = 2710.1(2) Å3 and Z = 3) has been refined to R1 = 0.046 on the basis of 1184 unique observed reflections. Nikmelnikovite is the first mineral species in the garnet supergroup that has a trigonal (rhombohedral) symmetry. The relationship between its unit cell and the pseudocubic (ideal garnet) unit cell can be described by the transformation matrix [10 | 01 | ½½½]. The crystal-chemical relations between the ideal Iad garnet and the nikmelnikovite structure type can be described by the following series of imaginary modifications: (1) the symmetry is lowered according to the Iad → R group-subgroup relationship; (2) the cation sites are split according to the following sequences: X → {X1, X2}; Y → {Y1, Y2, Y3, Y4}; Z → {Z1, Z2}; (3) the X sites remain fully occupied by Ca; (4) each Y site is occupied predominantly by a distinct chemical species: Y1 → Al (Al site), Y2 → Fe2+ (Fe1 site), Y3 → Fe3+ (Fe2 site), Y4 → vacancy (Mn site); (5) one of the Z sites (Z1) is occupied by Si, whereas the other site (Z2) is predominantly vacant. The crystal-chemical formula that takes into account the transition between the archetype and the nikmelnikovite structure type can be described as X{Ca12}Y[Fe2+Al4Fe3+2□]Z(Si6□6)O24(OH)20□4. The structural complexity of nikmelnikovite (4.529 bit/atom and 434.431 bit/cell, after H-correction) is higher than those for andradite, grossular and katoite, which is typical for low-temperature minerals formed after primary minerals with simpler structures.

KW - crystal structure

KW - garnet

KW - Kola peninsula

KW - Kovdor

KW - nikmelnikovite

KW - Russian Arctic

KW - COMPLEXITY

KW - OH

KW - DISSYMMETRIZATION

UR - http://www.scopus.com/inward/record.url?scp=85110173199&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/1c233dce-1734-3da4-b36a-2dbb6490fd15/

U2 - 10.1180/mgm.2021.55

DO - 10.1180/mgm.2021.55

M3 - Article

AN - SCOPUS:85110173199

VL - 85

SP - 620

EP - 626

JO - Mineralogical Magazine

JF - Mineralogical Magazine

SN - 0026-461X

IS - 4

ER -

ID: 88647542