Oxybismutomicrolite, a new pyrochlore-supergroup mineral from the Malkhan pegmatite field, Central Transbaikalia, Russia

Kasatkin, Anatoly V.; Britvin, Sergey N.; Peretyazhko, I. S.; Чуканов, Н. В.; Škoda, Radek; Agakhanov, Atali A.

doi:10.1180/mgm.2020.25

Cited by 12 publications

(7 citation statements)

References 29 publications

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“…Excluding synthetic oxy-compounds with a pyrochlore-type structure, well-studied natural pyrochlore-group minerals with O at the Z site are rare. Examples are ‘stibiobetafite’ from pegmatititic Vežná serpentinite, Czech Republic (Černý et al , 1979), ‘uranbetafite’ from foid-bearing syenite ejectum in pyroclastic rock, Vico volcanic complex, Italy (Cámara et al , 2004), pyrochlore from calcite–magnetite–forsterite phoscorite, Kovdor plutonic complex (Ivanyuk et al , 2018) and oxybismutomicrolite from granitic pegmatite, Malkhan, Central Transbaikalia, (Kasatkin et al , 2020) where compositional and single-crystal X-ray diffraction data suggest O dominance in the Z site.…”

Section: Discussionmentioning

confidence: 99%

“…Application of the current pyrochlore nomenclature and classification (Atencio et al , 2010; Christy and Atencio, 2013) revealed several problems associated with the new mineral names (e.g. Mitchell, 2015; Kasatkin et al , 2020). For example, all analytical data obtained during this investigation correspond to an ideal pyrochlore formula (CaNa)Nb 2 O 6 F (Table 1), which, ironically, is not considered by either Atencio et al (2010) or Christy and Atencio (2013).…”

Section: Samples and Methodsmentioning

confidence: 99%

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Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania

Zaitsev

Spratt

Shtukenberg

et al. 2020

MinMag

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The Quaternary carbonatite–nephelinite Kerimasi volcano is located within the Gregory rift in northern Tanzania. It is composed of nephelinitic and carbonatitic pyroclastic rocks, tuffs, tuff breccias and pyroclastic breccias, which contain blocks of different plutonic (predominantly ijolite) and volcanic (predominantly nephelinite) rocks including carbonatites. The plutonic and volcanic carbonatites both contain calcite as the major mineral with variable amounts of magnetite or magnesioferrite, apatite and forsterite. Carbonatites also contain accessory baddeleyite, kerimasite, pyrochlore and calzirtite. Zr and Nb minerals are rarely observed in rock samples, though they are abundant in eluvial deposits of carbonatite tuff/pyroclastic breccias in the Loluni and Kisete craters. Pyrochlore, ideally (CaNa)Nb2O6F, occurs as octahedral and cubo-octahedral crystals up to 300 μm in size. Compositionally, pyrochlore from Loluni and Kisete differs. The former is enriched in U (up to 19.4 wt.% UO2), light rare earth elements (up to 8.3 wt.% LREE2O3) and Zr (up to 14.4 wt.% ZrO2), and the latter contains elevated Ti (up to 7.3 wt.% TiO2). All the crystals investigated were crystalline, including those with high U content (a = 10.4152(1) Å for Loluni and a = 10.3763(1) Å for Kisete crystals). They have little or no subsolidus alteration nor low-temperature cation exchange (A-site vacancy up to 1.5% of the site), and are suitable for single-crystal X-ray diffraction analysis (R1 = 0.0206 and 0.0290; for all independent reflections for Loluni and Kisete crystals, respectively). Observed variations in the pyrochlore composition, particularly Zr content, from the Loluni and Kisete craters suggest crystallisation from compositionally different carbonatitic melts. The majority of pyrochlore crystals studied exhibit exceptionally well-preserved oscillatory- and sometimes sector-type zoning. The preferential incorporation of smaller and higher charged elements into more geometrically constrained sites on the growing surfaces explains the formation of the sector zoning. The oscillatory zoning can be rationalised by considering convectional instabilities of carbonatite magmas during their emplacement.

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Section: Discussionmentioning

confidence: 99%

Section: Samples and Methodsmentioning

confidence: 99%

Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania

Zaitsev

Spratt

Shtukenberg

et al. 2020

MinMag

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“…These minerals include bismutocolumbite (Peretyazhko et al, 1992), borocookeite (Zagorsky et al, 2003), oxybismutomicrolite (Kasatkin et al, 2020) and nioboixiolite-(Mn 2+ ) (Chukanov et al, 2023).…”

Section: Occurrencementioning

confidence: 99%

Fluor-rossmanite, □(Al₂Li)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃F, a new tourmaline supergroup mineral from Malkhan pegmatite field, Western Siberia, Russia

Kasatkin,

Nestola,

Day

et al. 2024

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Fluor-rossmanite, ideally □(Al2Li)Al6(Si6O18)(BO3)3(OH)3F, is a new mineral of the tourmaline supergroup, found at the Krutaya pegmatite, Malkhan pegmatite field, Zabaykalskiy Krai, Western Siberia, Russia. It forms an intermediate zone up to 3 mm thick in a chemically heterogeneous, concentrically zoned, polychrome tourmaline crystal 3 x 2 cm in size. The new mineral is light pink, transparent with a white streak and a vitreous lustre. It is brittle, with conchoidal fracture. Mohs' hardness is 7. The Dmeas = 3.07(2) g cm -3 and Dcalc = 3.071 g cm -3 . Optically, fluor-rossmanite is non-pleochroic, uniaxial (-), ω = 1.647(2), ε = 1.628(2) (589 nm).The empirical formula calculated on the basis of 31 anions (O+OH+F) is: X (□0.46Na0.32Ca0.20Pb0.02)Σ1.00 Y (Al1.84Li1.05Mn0.05Fe 2+ 0.02Ti0.02Cr0.01)Σ2.99 Z Al6.00 T (Si5.79Al0.21)Σ6.00 B2.99O27 V (OH)3 W [F0.44(OH)0.20O0.36]Σ1.00. Fluor-rossmanite is trigonal, R3m; the unit-cell parameters are:

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“…Oxybismutomicrolite ( Kasatkin et al, 2020 ), (Bi, #) 2 Ta 2 O 6 O, Fd

m, a 10.475 (1) Å, V 1149.38 Å 3 . IMA number: 2019-047.…”

Section: Microlite Groupunclassified

Pyrochlore-Supergroup Minerals Nomenclature: An Update

Atencio

2021

Front. Chem.

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The general formula of the pyrochlore-supergroup minerals is A2B2X6Y. The mineral names are composed of two prefixes and one root name (identical to the name of the group). The first prefix refers to the dominant anion (or cation or H2O or vacancy) of the dominant valence at the Y-site. The second prefix refers to the dominant cation of the dominant valence [or H2O or vacancy] at the A-site. Thirty-one pyrochlore-supergroup mineral species are currently distributed into four groups [pyrochlore (B = Nb, X = O), microlite (B = Ta, X = O), roméite (B = Sb5+, X = O), and elsmoreite (B = W, X = O)] and two unassigned members [hydrokenoralstonite (B = Al, X = F) and fluornatrocoulsellite (B = Mg, X = F)]. However, when the new nomenclature system of this supergroup was introduced (2010) only seven mineral species, namely, oxycalciopyrochlore, hydropyrochlore, hydroxykenomicrolite, oxystannomicrolite, oxystibiomicrolite, hydroxycalcioroméite, and hydrokenoelsmoreite, were valid. The seven species belong to the cubic crystal system and space group Fd3¯m and O is predominant in the X structural site. The 24 new mineral species described between 2010 and 2021 are cesiokenopyrochlore, fluorcalciopyrochlore, fluornatropyrochlore, hydrokenopyrochlore, hydroxycalciopyrochlore, hydroxynatropyrochlore, hydroxykenopyrochlore, hydroxymanganopyrochlore, hydroxyplumbopyrochlore, fluorcalciomicrolite, fluornatromicrolite, hydrokenomicrolite, hydroxycalciomicrolite, kenoplumbomicrolite, oxynatromicrolite, oxycalciomicrolite, oxybismutomicrolite, fluorcalcioroméite, hydroxyferroroméite, oxycalcioroméite, oxyplumboroméite, fluornatrocoulsellite, hydrokenoralstonite, and hydroxykenoelsmoreite. Among the new species, hydroxycalciomicrolite belongs to a different space group of the cubic system, i.e., P4232. There are also some mineral species that crystallize in the trigonal system. Hydrokenoelsmoreite occurs as 3C (Fd3¯m) and 6R (R3¯) polytypes. Hydrokenomicrolite occurs as 3C (Fd3¯m) and 3R (R3¯m) polytypes, of which the latter corresponds to the discredited “parabariomicrolite.” Fluornatrocoulsellite crystallizes as 3R (R3¯m) polytype. Surely there are several new pyrochlore-supergroup minerals to be described.

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Oxybismutomicrolite, a new pyrochlore-supergroup mineral from the Malkhan pegmatite field, Central Transbaikalia, Russia

Cited by 12 publications

References 29 publications

Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania

Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania

Fluor-rossmanite, □(Al₂Li)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃F, a new tourmaline supergroup mineral from Malkhan pegmatite field, Western Siberia, Russia

Pyrochlore-Supergroup Minerals Nomenclature: An Update

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Oxybismutomicrolite, a new pyrochlore-supergroup mineral from the Malkhan pegmatite field, Central Transbaikalia, Russia

Cited by 12 publications

References 29 publications

Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania

Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania

Fluor-rossmanite, □(Al2Li)Al6(Si6O18)(BO3)3(OH)3F, a new tourmaline supergroup mineral from Malkhan pegmatite field, Western Siberia, Russia

Pyrochlore-Supergroup Minerals Nomenclature: An Update

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Fluor-rossmanite, □(Al₂Li)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃F, a new tourmaline supergroup mineral from Malkhan pegmatite field, Western Siberia, Russia