Fluorosatropyrochlore

Fluorosatropyrochlore
Fluorosatropyrochlore crystals with honey-brown titanite on sanidine from Lagoa do Fogo in the Água de Pau massif, São Miguel island , Azores , Portugal (field of view: 2.53 mm)
General and classification
other names	IMA 2013-056
chemical formula	(Na, Pb, Ca, REE, U) 2 Nb 2 O 6 F
Mineral class (and possibly department)	Oxides and hydroxides
System no. to Strunz and to Dana	4.DH.15 ( 8th edition : IV / C.17) 02/08/01. ??
Crystallographic Data
Crystal system	cubic
Crystal class ; symbol	cubic hexakisoctahedral; 4 / m  3  2 / m
Space group	Fd 3 m (No. 227)
Lattice parameters	a  = 10.5053  Å
Formula units	Z  = 8
Physical Properties
Mohs hardness	4 to 4.5
Density (g / cm 3 )	5.275 (calculated)
Cleavage	no
Break ; Tenacity	clamshell; brittle
colour	brownish yellow to reddish orange, orange
Line color	light yellow
transparency	translucent to translucent
shine	Diamond luster
Crystal optics
Refractive index	n  = 2.10
Optical character	isotropic
Other properties
Special features	no fluorescence

Fluorosatropyrochlore is a very rare mineral from the mineral class of oxides and hydroxides . It crystallizes in the cubic crystal system having the composition (Na, Pb, Ca, REE, U) ₂ Nb ₂ O ₆ F, is therefore a sodium - niobate with additional fluoride ions.

Fluorosatropyrochlore occurs at its type locality in the form of xenomorphic grains and only occasionally subidiomorphic crystals with a maximum size of 0.25 mm. Idiomorphic crystals up to 1 mm in size have also been described.

The type locality of the fluorosatropyrochloride is the uranium and REE leading late variscan alkaline rock pluton of the Boziguoer intrusion ( coordinates of the Boziguoer intrusion ) near Baicheng in Bay County , Aksu Governorate , Xinjiang Uyghur Autonomous Region in China .

Etymology and history

During the processing of the late Variscan alkaline rock pluton of the Boziguoer intrusion, which leads to uranium and REE , a mineral emerged as a new member of the pyrochlore group at Baicheng in Bay County , Aksu Governorate, Xinjiang Uyghur Autonomous Region in China. After determining the petrographic properties, the chemical composition, the spectral properties and the crystal structure with the aid of a combination of polarization microscopy , microprobe analysis , X-ray diffraction and FTIR spectroscopy , the new mineral was presented to the International Mineralogical Association (IMA), which it was in 2013 under the provisional Designation "IMA 2013-056" recognized. The first scientific description of this mineral was made in 2015 by a Chinese research team with Yin Jingwu, Li Guowu, Yang Guangming, Ge Xiangkun, Xu Haiming and Wang Jun in the Canadian science magazine The Canadian Mineralogist .

The authors named the new mineral in accordance with the nomenclature of the pyrochlore upper group due to its chemical composition with an A position dominated by sodium , a B position dominated by niobium and a Y position dominated by fluorine as fluoronatropyrochlore ( English: fluornatropyrochlore ).

The type material for fluorosatropyrochlore is stored under catalog number M12183 (holotype) in the collection of the Chinese Geological Museum in Beijing , China.

During the revision of the nomenclature of the "pyrochlore group" to the new pyrochlore upper group (pyrochlore supergroup) introduced in 2010, it turned out that a mineral with a composition that would justify the designation as "fluoronatropyrochlore" was already used by Pavel M Kartashov had been examined - but the results remained unpublished.

classification

The current classification of the International Mineralogical Association (IMA) counts the fluorosatropyrochlore to the pyrochlore upper group with the general formula A _{2– m} B ₂ X _{6– w} Y _{1– n} , in which A , B , X and Y different positions in the structure the minerals of the pyrochlore upper group with A  = Na, Ca, Sr, Pb ²⁺ , Sn ²⁺ , Sb ³⁺ , Y, U, □, or H ₂ O; B = Ta, Nb, Ti, Sb ⁵⁺ or W; X = O, OH or F and Y = OH ^- , F, O, □, H ₂ O or very large (>> 1.0 Å) monovalent cations such as K, Cs or Rb. To pyrochlore supergroup include not only Fluornatropyrochlor still Fluorcalciomikrolith , Fluornatromikrolith , Hydrokenomikrolith , Hydroxycalciomikrolith , Hydroxykenomikrolith , Kenoplumbomikrolith , Oxynatromikrolith , Oxystannomikrolith , Oxystibiomikrolith , Cesiokenopyrochlor , Fluorcalciopyrochlor , Hydrokenopyrochlor , Hydropyrochlor , Hydroxycalciopyrochlor , Hydroxykenopyrochlor , Hydroxymanganopyrochlor , Hydroxynatropyrochlor , Oxycalciopyrochlor , Fluorcalcioroméit , Hydroxycalcioroméit , Hydroxyferroroméit , Oxycalcioroméit , Oxyplumboroméite , Hydrokenoelsmoreit , Hydroxykenoelsmoreit , Fluornatrocoulsellit and Hydrokenoralstonit . Together with cesiokenopyrochlor, fluorcalciopyrochlor, hydrokenopyrochlore, hydropyrochlore, hydroxycalciopyrochlor, hydroxykenopyrochlor, hydroxymanganopyrochlor, hydroxynatropyrochlore and oxycalciopyrochlor within the pyrochlore upper group, the pyrochlore group forms .

The 8th edition of the mineral classification according to Strunz , which is now out of date, but is still in use in some cases, does not yet list fluoronatropyrochlore. It would belong to the mineral class of "oxides and hydroxides" and there to the general division of "oxides with a metal: oxygen ratio = 2: 3 (M ₂ O ₃ and related compounds)", where together with bariopyrochlore (discredited 2010, possibly " Zero-valent-dominant pyrochlore "), bismuthopyrochlore (discredited 2010, possibly" Oxynatropyrochlore "), Calciobetafit (discredited 2010), Ceriopyrochlor- (Ce) (discredited 2010, possibly" Fluorkenopyrochlore "), Kalipyrochlore (2010 redefined to hydropyrochlore), Plumbopyrochlor (discredited 2010, possibly "Oxyplumbopyrochlor" or "Kenoplumbopyrochlor"), Pyrochlore (discredited 2010, since then group and parent group name; this includes the possibly new species "Oxynatropyrochlor", "Hydroxycalciopyrochlor", "Fluorcalciopyrochlor" and "Fluorkenopyrochlor"), Uranpyrochlor (discredited 2010, possibly “Oxynatropyrochlor”), Strontiopyrochlor (discredited 2010, possibly “Fluorstrontiopyroc hlor "or" Fluorkenopyrochlor ") and Yttropyrochlor- (Y) (discredited 2010, possibly" Oxyyttropyrochlor- (Y) ") the" Pyrochlore Group, Pyrochlore Subgroup "with the system no. IV / C.17 would have formed.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies fluoronatropyrochlore in the category of "oxides with the molar ratio of metal: oxygen = 1: 2 and comparable". However, this section is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral according to its composition and structure is classified in the sub-section “With large (± medium-sized) cations; Layers of edge-linked octahedra ”can be found, where together with all representatives of the pyrochlore, microlith, Betafit, Roméit and Elsmoreit groups, the pyrochlore supergroup with the system no. 4.DH.15 forms. Fluornatropyrochlor is found together with Fluorcalciopyrochlor , Fluorkenopyrochlor , Fluorstrontiopyrochlor , Hydropyrochlor (formerly Kalipyrochlor ), Hydroxycalciopyrochlor , Kenoplumbopyrochlor , Oxycalciopyrochlor (formerly Stibiobetafit ), Oxynatropyrochlor- (formerly Stibiobetafit ), Oxynatropyrochlor- , Oxyrottyrochlor , Oxyrottyrochlor , Oxyplumbopyrochlor .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , does not yet know the fluorine atropyrochlore. It would be classified in the class of "oxides and hydroxides", but there in the department of "multiple oxides with Nb, Ta and Ti". Here he was, along with pyrochlore , Kalipyrochlor , Bariopyrochlor , Yttropyrochlor- (Y) , Ceriopyrochlor- (Ce) , Plumbopyrochlor , Uranpyrochlor , Strontiopyrochlor and Bismutopyrochlor (all since 2010 discredited. See under classification of minerals by Strunz 8th edition) the "pyrochlore subgroup; Nb> Ta; (Nb + Ta)> 2 (Ti) “with the system no. 08.02.01 to be found within the subsection of " Multiple oxides with Nb, Ta and Ti with the formula A ₂ (B ₂ O ₆ ) (O, OH, F) ".

Chemism

Ten microprobe analyzes on two single grains yielded mean values ​​of 6.80% Na ₂ O; 0.01% K ₂ O; 2.01% CaO; 0.01% MgO; 0.05% FeO; 0.03% SrO; 16.17% PbO; 4.29% Ce ₂ O ₃ ; 1.65% La ₂ O ₃ ; 0.41% Nd ₂ O ₃ ; 0.42% Y ₂ O ₃ ; 0.03% SiO ₄ ; 1.36% TiO ₂ ; 5.91% UO ₂ ; 3.00% Ta ₂ O ₅ ; 53.42% Nb ₂ O ₅ ; 3.19% F; 0.02% Cl; 0.48% ThO ₂ ; 0.01% Sb ₂ O ₅ ; 0.01% ZrO ₂ ; 0.04% MnO; 0.34% SnO ₂ and [(O ≡ F, Cl) -1.35%, sum = 98.21%]. On the basis of seven anions per formula unit, the empirical formula (Na _1.03 Pb _0.34 Ca _0.17 U _0.10 Th _0.01 Ce _0.12 La _0.05 Y _0.02 Nd _0.01 ) _{Σ = 1.85} (Nb _1.88 Ti _0.08 Ta _0.06 Sn _0.01 ) _{Σ = 2.03} O _6.21 F _0.79 calculated, _resulting in (Na, Pb, Ca, REE, U) ₂ Nb ₂ O ₆ F has been simplified.

Of all the minerals, only fluoronatropyrochlore contains the element combination Na - Nb - O - F. In addition, bornemanite , Na ₆ BaTi ₂ Nb (Si ₂ O ₇ ) ₂ (PO ₄ ) O ₂ (OH) F; Nacareniobsite- (Ce) , NbNa ₃ Ca ₃ (Ce, REE) (Si ₂ O ₇ ) ₂ OF ₃ ; Kentbrooksite , (Na, REE) ₁₅ (Ca, REE) ₆ (Mn ²⁺ , Fe ²⁺ ) ₃ Zr ₃ Nb [Si2 ₅ O ₇₄ ] F ₂ · 2H ₂ O; Vuonnemit , Na ₁₁ Ti ⁴⁺ Nb ₂ (Si ₂ O ₇ ) ₂ (PO ₄ ) ₂ O ₃ (F, OH); and zvyaginite , NaZnNb ₂ Ti [Si ₂ O ₇ ] ₂₀ (OH, F) ₃ (H ₂ O) ₄  + (x <1); chemical similarities to fluorosatropyrochlore.

Within the pyrochlore upper group there are theoretically a multitude of substitution possibilities due to the four different positions to be occupied. Fluoronatropyrochlore is the Na-dominant analogue of the Ca-dominated Fluorcalciopyrochlore and the F-dominant analogue of the OH-dominated Hydroxynatropyrochlore. Across all subgroups, fluoronatropyrochlore is the Nb-dominant analogue of the Ta-dominated fluoronatromicrolite and the Al ³⁺ -dominated fluoronatrocoulsellite.

Crystal structure

Fluoronatropyrochlore crystallizes in the cubic crystal system in the space group Fd 3 m (space group no. 227) with the lattice parameter a = 10.5053  Å and eight formula units per unit cell .

The crystal structure of the Fluornatropyrochlors is by edge-sharing NbO ₆ - octahedron characterized which form a chain in the direction of [110], whereas NbO ₆ octahedra with shared corners form a three-dimensional cage. The sodium atoms sit in the center of this cage, which is formed by six oxygen and two fluorine atoms. This cube-shaped NaO ₆ F ₂ - polyhedra are connected together by common edges. The cations Na and Nb occupy positions 16 c and 16 d , respectively , while O and F are in positions 48 f and 8 a . Nb is surrounded by six oxygen atoms in octahedral coordination, while Na is hexahedrally coordinated by two fluorine and six oxygen atoms. The six oxygen atoms are arranged in the form of a bumpy ring, while the fluorine atoms may be linearly coordinated.

Fluorosatropyrochlore is isotypic (isostructural) to all other representatives of the pyrochlore upper group which crystallize in space group Fd 3 m (space group no. 227) .

properties

morphology

At its type locality, Fluorosatropyrochlore forms allotriomorphic grains and at most subidiomorphic crystals up to 0.25 mm in size. At the locality "Lagoa do Fogo", Maciço de Água de Pau, São Miguel, Ilhas dos Açores, Portugal, it is found in idiomorphic, octahedral crystals up to approx. 1 mm in size.

physical and chemical properties

The crystals of the fluorine atropyrochloride are brownish-yellow to reddish-orange at the type locality, whereas in “Lagoa do Fogo”, São Miguel, Azores, they are bright orange. Their line color , however, is always light yellow. The surfaces of the translucent to transparent Fluorosatropyrochloride show a diamond-like sheen , which agrees well with the very high value for the refraction of light (n = 2.10). Fluorosatropyrochlore is optically isotropic.

Fluorosatropyrochlore is neither cleavable nor divisible. Due to its brittleness , however , it breaks in a similar way to quartz , with the fracture surfaces being shell-shaped. With a Mohs hardness of 4 to 4.5, the mineral is one of the medium-hard minerals and, like the reference mineral fluorite, can be scratched more or less easily with a pocket knife. The calculated density for fluoronatropyrochlore is 5.275 g / cm³.

Fluornatropyrochlor is neither in the long wavelength even in the short wavelength UV light , a fluorescent . There is no information on cathodoluminescence under the electron beam for the mineral.

Education and Locations

The type locality for fluorosatropyrochlore is the late Variscan alkali rock pluton of the Boziguo intrusion, 43 km north of Baicheng in Bay County , Aksu Governorate , Xinjiang Uyghur Autonomous Region in China . The intrusion leads to extensive niobium-tantalum mineralization and is characterized by high contents of rubidium , uranium , thorium , zirconium and rare earth metals . In the intrusive body there are two different mining districts with mineralizations formed at different times, although there are also different mineral parageneses in the two mining areas. Xenotime (Y) , chevkinite (Ce) and fergusonite (Y) are mainly found as accessories in the aegirine granite of the western part, while thorite and columbite (Fe) are mainly contained in the biotite adamellite of the eastern part.

Typical accompanying minerals of fluorine atropyrochloride at its type locality are microcline , albite , aegirine , a sodium-containing amphibole , biotite , zirconium , rutile , thorite, fluorite , fluocerite (Ce) , columbite (Fe), xenotime (Y), astrophyllite , chevkinite (Ce) and fergusonite (Y).

As a very rare mineral formation, fluorosatropyrochlore could only be described from around ten sites so far (status 2018).

In addition to the type locality, the following sites are known:

• the "Nechalacho" deposit in the syenite complex of Thor Lake, alkali rock complex of Blachford Lake near Yellowknife , Mackenzie District, Northwest Territories , Canada
• the quarry of Poudrette Quarry (also Demix Quarry, Uni-Mix Quarry, Desourdy Quarry and Carrière Mont Saint-Hilaire) on Mont Saint-Hilaire , Regional County Community (MRC) La Vallée-du-Richelieu , Montérégie , Québec , Canada
• the ilmenite deposits near Girardville in the regional county town of Maria-Chapdelaine , Saguenay-Lac-Saint-Jean , Québec, Canada
• the “Maoniuping” deposit ( coordinates of the REE “Maoniuping” deposit ) in Mianning County , Liangshan Autonomous District , Sichuan Province , China; this is the world's second largest REE deposit, which was originally specified as the type locality for fluoronatropyrochlore instead of the “Boziguoer intrusion”.
• the quarries "In den Dellen", Niedermendig near Mendig , Laacher See complex, Eifel , Rhineland-Palatinate , Germany
• the phonolite quarry on Mount Köves near Hosszúhetény , Mecsek Mountains , Baranya County , Hungary
• the prospectus “Ampasibitika” at Antsirabe, District Ambanja , Region Diana , former Province Antsiranana , Madagascar
• complex Ta-Nb-Zr-REE mineralization in the massif of Khaldzan Buragtag, Mongolian Altai , Chowd-Aimag , Mongolia
• Finds at the ruins of Lombadas ("imediação das ruinas de Lombadas"), Lagoa do Fogo , Serra de Água de Pau, São Miguel , Ilhas dos Açores ( Azores ), Portugal

Sites for fluoronatropyrochlore in Austria and Switzerland are therefore unknown.

use

Fluorosatropyrochlore is of no practical importance due to its rarity.

See also

• Systematics of the minerals
• List of minerals

literature

• Yin Jingwu, Li Guowu, Yang Guangming, Ge Xiangkun, Xu Haiming, Wang Jun: Fluornatropyrochlore, a new pyrochlore supergroup mineral from the Boziguoer rare earth element deposit, Baicheng County, Akesu, Xinjiang, China . In: The Canadian Mineralogist . tape 53 , 2015, p. 455–460 , doi : 10.3749 / canmin.1500007 (English, edu.cn [PDF; 1.6 MB ; accessed on September 24, 2018]).

Web links

Commons : Fluoronatropyrochlore  - Collection of images, videos and audio files

• Mineral Atlas: Fluorosatropyrochlore (Wiki)
• Mindat - Fluorosatropyrochlore (English)

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag} Yin Jingwu, Li Guowu, Yang Guangming, Ge Xiangkun, Xu Haiming, Wang Jun: Fluornatropyrochlore, a new pyrochlore supergroup mineral from the Boziguoer rare earth element deposit, Baicheng County, Akesu, Xinjiang, China . In: The Canadian Mineralogist . tape 53 , 2015, p. 455–460 , doi : 10.3749 / canmin.1500007 (English, edu.cn [PDF; 1.6 MB ; accessed on September 24, 2018]).
2. ↑ ^{a b c} Bernd Ternes: Minerals from the Azores island of São Miguel, Portugal . In: Lapis . tape 24 , no. 1 , 1999, p. 20–42 ( wordpress.com [PDF; 8.8 MB ; accessed on September 24, 2018]).
3. ^ Donald David Hogarth: Classification and nomenclature of the pyrochlore group . In: The American Mineralogist . tape 62 , 1977, pp. 403-410 (English, rruff.info [PDF; 849 kB ; accessed on September 3, 2018]).
4. ^ ^{A b} Daniel Atencio, Marcelo B. Andrade, Andrew G. Christy, Reto Gieré, Pavel M. Kartashov: The Pyrochlore supergroup of minerals: Nomenclature . In: The Canadian Mineralogist . tape 48 , 2010, p. 673–698 , doi : 10.3749 / canmin.48.3.673 (English, rruff.info [PDF; 1,4 MB ; accessed on August 30, 2018]).
5. ^ Andrew G. Christy, Daniel Atencio: Clarification of the status of species in the pyrochlore supergroup . In: Mineralogical Magazine . tape 77 , no. 1 , 2013, p. 13–20 , doi : 10.1180 / minmag.2013.077.1.02 (English, main.jp [PDF; 85 kB ; accessed on August 30, 2018]).
6. ↑ ^{a b c} Mindat - Fluornatropyrochlore , accessed on September 24, 2018 (English)
7. ↑ Li Guowu, Yang Guangming, Lu Fude, Xiong Ming, Ge Xiangkun, Pan Baoming, Jeffrey de Fourestier: Fluorcalciopyrochlor, a new mineral species from Bayan Obo, Inner Mongolia, PR China . In: The Canadian Mineralogist . tape 54 , no. 5 , 2016, p. 1285–1291 , doi : 10.3749 / canmin.1500042 (English).
8. ↑ Gregory Yu. Ivanyuk, Victor N. Yakovenchuk, Taras L. Panikorovskii, Nataliya Konoplyova, Yakov A. Pakhomovsky, Ayya V. Bazai, Vladimir N. Bocharov, Sergey V. Krivovichev: Hydroxynatropyrochlore, (Na, С a, Ce) ₂ Nb ₂ O ₆ (OH), a new member of the pyrochlore group from the Kovdor phoscorite-carbonatite pipe (Kola Peninsula, Russia) . In: Mineralogical Magazine . doi : 10.1180 / minmag.2017.081.102 (English, accepted article for Mineralogical Magazine, not printed yet).
9. ↑ Thomas Witzke, Manfred Steins, Thomas Doering, Walter Schuckmann, Reinhard Wegner, Herbert Pöllmann: Fluornatromicrolite, (Na, Ca, Bi) ₂ Ta ₂ O ₆ F, a new mineral species from Quixaba, Paraíba, Brazil . In: The Canadian Mineralogist . tape 49 , 2011, p. 1105–1110 , doi : 10.3749 / canmin.49.4.1105 (English).
10. ^ Daniel Atencio, Marcelo B. Andrade, Artur C. Bastos Neto, Vitor P. Pereira: Ralstonite renamed Hydrokenoralstonite, Coulsellite renamed Fluornatrocoulsellite, and their incorporation into the Pyrochlore supergroup . In: The Canadian Mineralogist . tape 55 , no. 1 , 2017, p. 115–120 , doi : 10.3749 / canmin.1600056 (English, researchgate.net [PDF; 624 kB ; accessed on September 24, 2018]).
11. ↑ Mindat - Number of locations for fluoronatropyrochlore , accessed on September 24, 2018 (English)
12. ↑ ^{a b} List of locations where fluoronatropyrochlore is found in the Mineralienatlas and Mindat (accessed on September 24, 2018)
13. ↑ Yin Jingwu, Li Guowu, Yang Guangming, Xiong Ming, Ge Xiangkun, Pan Baoming: Fluornatropyrochlore, IMA 2013-056. CNMNC Newsletter No. October 17, 2013, page 3003 . In: Mineralogical Magazine . tape 77 , 2013, p. 2997-3005 (English).