Hydrokenopyrochlore, (□,#)2Nb2O6·H2O, a new species of the pyrochlore supergroup from the Sahatany Pegmatite Field, Antananarivo Province, Madagascar

Biagioni, Cristian; Meisser, Nicolas; Nestola, Fabrizio; Pasero, Marco; Robyr, Martin; Roth, Philippe; Schnyder, C.; Gieré, Reto

doi:10.1127/ejm/2018/0030-2761

Cited by 10 publications

(4 citation statements)

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“…It can be noted that in L1 and L14 crystals (Table 4) the structural vacancies rather than the aqueous species are dominant at (A + A′). Therefore, on the basis of the current nomenclature system (Atencio et al 2010;Atencio 2021), they are to be referred to as hydrokenopyrochlore [ideal formula (□,#)2Nb2O6•H2O (Biagioni et al 2018)].…”

Section: Resultsmentioning

confidence: 99%

“…Ion-exchange processes may take place at the interstitial sites located within the tunnels, especially when they are occupied by highly mobile species (such as H2O) or when they are partially vacant, which is a common feature for natural, strongly weathered pyrochlores (e.g., hydropyrochlore; Ercit et al 1994;Lumpkin and Ewing 1995, and hydrokenopyrochlore;Biagioni et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Crystallographic insights into monovalent thallium incorporation: Exploring hydropyrochlore structure for environmental remediation

Taddei,

Bindi,

Lepore

et al. 2024

American Mineralogist

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Hydropyrochlore, ideally (H2O,◻)2Nb2(O,OH)6(H2O), is a cubic mineral (space group Fd3 " m, a = 10.56-10.59 Å, Z = 8) belonging to the pyrochlore supergroup (general formula: A2-mB2X6-wY1-n).The K-rich variety of this species is unique to the Lueshe syenitic-carbonatitic deposit (D.R. Congo), where it occurs as the alteration product of primary (Ca,Na)2Nb2O6F pyrochlores. The structure of this mineral is made of a B2X6 (B = Nb, Ti; X = O, OH) framework that generates tunnels along the This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crystallographic insights into monovalent thallium incorporation: Exploring hydropyrochlore structure for environmental remediation

Taddei,

Bindi,

Lepore

et al. 2024

American Mineralogist

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“…Hydrokenopyrochlore ( Biagioni et al, 2018 ), (□, #) 2 Nb 2 O 6 (H 2 O), Fd

m, a 10.4887(8) Å, V 1153.9 Å 3 . IMA number: 2017-005.…”

Section: Pyrochlore Groupmentioning

confidence: 99%

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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“…10 -----*: Hydroxyplumbopyrochlore, (Pb 1.5 ,□ 0.5 )Nb 2 O 6 (OH), (this study) 1: Hydroxynatropyrochlore, (Na,Сa,Ce) 2 Nb 2 O 6 (OH), (Ivanyuk et al, 2017) 2: Fluornatropyrochlore, (Na,Pb,Ca,REE,U) 2 Nb 2 O 6 F, (Yin et al, 2015) 3: Hydroxycalciopyrochlore, (Ca,Na,U,□) 2 (Nb,Ti) 2 O 6 (OH), (Yang et al, 2014) 4: Fluorcalciopyrochlore, (Ca,Na) 2 (Nb,Ti) 2 O 6 F, (Li et al, 2016) 5: Oxycalciopyrochlore, Ca 2 Nb 2 O 6 O, (Atencio et al, 2010) 6: Hydropyrochlore, (H 2 O,□) 2 Nb 2 (O,OH) 6 (H 2 O), (Atencio et al, 2010) 7: Hydroxykenopyrochlore, (□,Ce,Ba) 2 (Nb,Ti) 2 O 6 (OH,F), (Miyawaki et al, 2017) 8: Hydrokenopyrochlore, (□,Sb 3+ ,Na) 2 Nb 2 O 6 ⋅H 2 O, (Biagioni et al, 2017) 9: Cesiokenopyrochlore, □Nb 2 (O,OH) 6 Cs 1-x , (Agakhanov et al, 2017) 10: Hydroxymanganopyrochlore, (Mn,Th,Na,Ca,REE) 2 (Nb,Ti) 2 O 6 (OH), (Chukanov et al, 2013) Fig. 1.…”

Section: Raman Spectrummentioning

confidence: 99%

Hydroxyplumbopyrochlore, (Pb_1.5,□_0.5)Nb₂O₆(OH), a new member of the pyrochlore group from Jabal Sayid, Saudi Arabia

Fan

et al. 2020

MinMag

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A new mineral species of the pyrochlore supergroup, hydroxyplumbopyrochlore (IMA2018-145), (Pb1.5,□0.5)Nb2O6(OH), has been discovered in the Jabal Sayid peralkaline granitic complex of the Arabian Shield, Saudi Arabia. It is associated with quartz, microcline, ‘biotite’, rutile, zircon, calcite, rhodochrosite, columbite-(Fe), goethite, thorite, bastnäsite-(Ce), xenotime-(Y), samarskite-(Y), euxenite-(Y), hydropyrochlore and fluornatropyrochlore. Hydroxyplumbopyrochlore usually shows euhedral octahedra, slightly rhombic dodecahedra and cubes or their combination (0.01–0.06 mm). The mineral is pale yellow to pale brown, transparent with white streak, and has adamantine to transparent lustre. It is brittle with conchoidal fracture. No cleavage or parting are observed. It is isotropic and non-fluorescent. The average microhardness is 463.4 kg mm–2. The calculated density is 6.474 g cm–3. Hydroxyplumbopyrochlore belongs to the cubic crystal system and exhibits the space group Fd $\bar{3}$ m with unit-cell parameters a = 10.5456(6) Å, V = 1172.8(2) Å3 and Z = 8. Electron microprobe analysis gave (6-point average composition, wt.%): CaO 0.32, SrO 0.16, FeO 0.17, Ce2O3 0.07, Pr2O3 0.02, PbO 51.69, Nb2O5 40.06, SiO2 0.05, TiO2 1.68, Ta2O5 4.74, H2Ocalc 0.95, total 99.90, yielding the empirical formula (Pb1.34Ca0.03Fe0.01Sr0.01□0.61)Σ2(Nb1.75Ti0.12Ta0.12Si0.01)Σ2O6(OH0.53O0.08□0.39)Σ1, where □ = vacancy. The Raman spectrum of hydroxyplumbopyrochlore contains the characteristic bands of O–H vibrations and no bands for H2O vibrations.

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Hydrokenopyrochlore, (□,#)2Nb2O6·H2O, a new species of the pyrochlore supergroup from the Sahatany Pegmatite Field, Antananarivo Province, Madagascar

Cited by 10 publications

References 26 publications

Crystallographic insights into monovalent thallium incorporation: Exploring hydropyrochlore structure for environmental remediation

Crystallographic insights into monovalent thallium incorporation: Exploring hydropyrochlore structure for environmental remediation

Pyrochlore-Supergroup Minerals Nomenclature: An Update

Hydroxyplumbopyrochlore, (Pb_1.5,□_0.5)Nb₂O₆(OH), a new member of the pyrochlore group from Jabal Sayid, Saudi Arabia

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Hydrokenopyrochlore, (□,#)2Nb2O6·H2O, a new species of the pyrochlore supergroup from the Sahatany Pegmatite Field, Antananarivo Province, Madagascar

Cited by 10 publications

References 26 publications

Crystallographic insights into monovalent thallium incorporation: Exploring hydropyrochlore structure for environmental remediation

Crystallographic insights into monovalent thallium incorporation: Exploring hydropyrochlore structure for environmental remediation

Pyrochlore-Supergroup Minerals Nomenclature: An Update

Hydroxyplumbopyrochlore, (Pb1.5,□0.5)Nb2O6(OH), a new member of the pyrochlore group from Jabal Sayid, Saudi Arabia

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Hydroxyplumbopyrochlore, (Pb_1.5,□_0.5)Nb₂O₆(OH), a new member of the pyrochlore group from Jabal Sayid, Saudi Arabia