Horváthit- (Y)

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Horváthit- (Y)
Horváthite- (Y) -299248.jpg
Pale pink colored "wagon wheel" -like horváthite (Y) crystals from the "Poudrette Qarry", Mont Saint-Hilaire , La Vallée-du-Richelieu RCM, Montérégie , Québec , Canada (field of view: 3.2 mm × 2, 3 mm)
General and classification
other names
  • IMA 1996-032
  • Unnamed (MSH UK-104)
chemical formula
  • NaY (CO 3 ) F 2
  • NaY [F 2 | CO 3 ]
Mineral class
(and possibly department) 		Carbonates and nitrates
System no. to Strunz
and to Dana 		5.BD.25 ( 8th edition : V / C.07-066)
16a.01.10.01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Pmcn (No. 62, position 5)Template: room group / 62.5
Lattice parameters a  = 6.964  Å ; b  = 9.173 Å; c  = 6.302 Å
Formula units Z  = 4
Frequent crystal faces {100}> {001}> {010} as well as {110}, {011} and {101}
Physical Properties
Mohs hardness 4th
Density (g / cm 3 ) > 3.3 (measured); 3.61 (calculated)
Cleavage very good after {100}, good after {010}
Break ; Tenacity uneven; brittle
colour colorless to pale beige, pale pink
Line color White
transparency translucent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.457
n β  = 1.543
n γ  = 1.622
Birefringence δ = 0.165
Optical character biaxial negative
Axis angle 2V = 82 ° (measured), 2V = 83 ° (calculated)
Pleochroism weak from Y  ≈  Z  = pale brown to X  = colorless

Horváthit- (Y) is a very rarely occurring mineral from the mineral class of " carbonates and nitrates ". It crystallizes in the orthorhombic crystal system with the idealized chemical composition NaY (CO 3 ) F 2 and is therefore chemically a sodium - yttrium - carbonate with additional fluorine ions. Horváthit- (Y) is one of the REE-containing fluorocarbonates.

Horváthit- (Y) can be found in two different habitus variants . It mainly forms isometric to elongated blocky, columnar or fan-shaped aggregates up to 1.2 cm in length, which have a "cartwheel" -like or cylindrical habit. These aggregates consist of individual, radially arranged, striped and prismatic crystals from 1 mm to 5 mm in length. The second habit is formed from (100) thin-tabular crystals stacked in parallel on (100). The length of these crystals decreases continuously from the center of the stack outwards, so that this parallel intergrowth of many crystals looks like a grooved single crystal when viewed from the surface.

The type locality of the Horváthit- (Y) is the 7th level of the passage- shaped "Poudrette-Pegmatite" opened up by the "Poudrette Quarry" ( coordinates of the Poudrette Quarry ) in Mont Saint-Hilaire , Regional County Community of La Vallée-du-Richelieu , Montérégie , Quebec , Canada .

Etymology and history

The mineral later called Horváthit- (Y) was first found in 1994 by Steve and Janet Cares on the 7th floor in the "Poudrette Quarry" and presented to George Yanji Chao of Carleton University in Ottawa , Canada , who recognized it as a possibly new mineral species . In 1997 and 1998, further material with significantly more horváthite (Y) was found in the same quarry on the 8th level. After completing the investigations and determining all relevant data, this mineral was submitted to the International Mineralogical Association (IMA), which recognized it as a new mineral in 1996 under the provisional designation "IMA 1996-032".

In 1997, the first scientific description of this mineral was made by a team of Canadian scientists with Joel D. Grice from the Canadian Museum of Nature (CMN) in Ottawa, and George Yanji Chao in the Canadian science magazine The Canadian Mineralogist as Horváthit- (Y) ( English Horváthite - (Y) ). They named the mineral after the Hungarian-Canadian amateur simalogist Lázló Horváth (* 1937) and his Swiss-Canadian wife Elsa Pfenninger-Horváth (* 1947). The couple has made a great contribution to the collection, investigation and documentation of the minerals of Mont Saint-Hilaire. They published numerous articles, provided many scientists with valuable research material and provided entire suites of minerals from Mont Saint-Hilaire to many museums around the world. Lázló Horváth - and z. T. also Elsa Pfenninger-Horváth - are co-authors of several first descriptions of minerals from alkali rock pegmatites such as B. Niveolanit , Lecoquit- (Y) , Peatit- (Y) , Ramikit- (Y) , Bobshannonite and Laverovite . The Levinson modifier in horváthite- (Y) [the suffix "- (Y)"] indicates the dominant rare earth metal (here: yttrium), as the IMA guidelines require when naming REE-containing minerals.

The type material for Horváthite- (Y) (holotype) is kept in the collection of the Canadian Museum of Nature , Ottawa, Canada (catalog number CMNMC 81536).

classification

Since the Horváthit- (Y) was only recognized as an independent mineral in 1996 and was first described in 1997, it is not listed in the 8th edition of the Strunz mineral classification, which has been obsolete since 1982 . In the "Lapis mineral directory", which was last updated in 2018 and which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the mineral and system no. V / C.07-066 , which in the "Lapis system" corresponds to the mineral class of "carbonates, nitrates and borates" and there the section "anhydrous carbonates, with foreign anions". There is Horváthit- (Y) together with Bastnäsit- (Y) , Bastnäsit- (La) , Bastnäsit- (Ce) , Bastnäsit- (Nd) , Hydroxylbastnäsit- (La) , Hydroxylbastnäsit- (Ce) , Hydroxylbastnasit- (Nd) , Kozoit- (La) , Kozoit- (Nd) , Parisit- (Ce) , Parisit- (Nd) , Röntgenit- (Ce) , Synchisit- (Y) , Synchisit- (Ce) , Synchisit- (Nd) , Huanghoit - (Ce) , Qaqarssukit- (Ce) , Cebait- (Ce) , Kukharenkoit- (La) , Kukharenkoit- (Ce) , Zhonghuacerit- (Ce) , Cordylit- (La) , Cordylit- (Ce) , Lukechangit- ( Ce) , Mineevit- (Y) , Reederit- (Y) and Micheelsenit combined in the "Bastnäsit Group".

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns the Horváthit- (Y) to the newly defined class of “carbonates and nitrates” and there in the department of “carbonates with additional Anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved and / or the metals primarily involved in the compound, so that the mineral can be found in the sub-section "With rare earth elements (REE)", where it is the only one, depending on its composition Member of the unnamed group with the system no. 5.BD.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns horváthite- (Y) to the common class of "carbonates, nitrates and borates" and there in the category of "carbonates - hydroxyl or halogen". Here he is the only member of the unnamed group 16a.01.10 within the subdivision “ Carbonates - Hydroxyl or Halogen - in the Bastnäsite / Synchisit / Parisitgruppen ”.

Chemism

Mean values from two microprobe analyzes on a horváthite (Y) grain from the type locality yielded 45.07% Y 2 O 3 ; 0.45% Gd 2 O 3 ; 0.12% Tb 2 O 3 ; 2.49% Dy 2 O 3 ; 0.81% Ho 2 O 3 ; 3.02% Er 2 O 3 ; 1.64% Yb 2 O 3 ; 1.86% CaO; 12.62% Na 2 O; 17.22% F and 19.83% CO 2 (−O = F 27.23%, total 97.90%). The amount of CO 2 was calculated according to the stoichiometry from the results of the crystal structure analysis. From the analysis was based on three oxygen -atoms the empirical formula (Na 0.90 Ca 0.07 ) Σ = 0.97 (Y 0.89 He 0.04 Dy 0.03 Yb 0.02 Gd 0, 01 Ho 0.01 ) Σ = 1.00 (CO 3 ) F 2.01 , which can be idealized to NaY (CO 3 ) F 2 . The idealized formula corresponds to the official formula of the IMA for the Horváthit- (Y). The simplified formula calls for 5.72% carbon; 22.87% oxygen; 18.10% fluorine; 10.95% sodium and 42.36% yttrium. Horváthit- (Y) is one of the REE-containing fluorocarbonates.

The element combination Na – Y – C – O – F is unique among the currently known minerals; so there are no minerals with a chemical composition with the same chemical elements as horváthite- (Y). On the other hand, Mineevit- (Y), Na 25 Ba (Y, Gd, Dy) 2 (CO 3 ) 11 (HCO3) 4 (SO 4 ) 2 F 2 Cl, Peatit- (Y) , Li 4 Na 12 Y are chemically similar 12 (PO 4 ) 12 (CO 3 ) 4 (F, OH) 8 , Ramikit- (Y) , Li 4 (Na, Ca) 12 Y 6 Zr 6 (PO 4 ) 12 (CO 3 ) 4 O 4 [( OH), F] 4 , and Reederit- (Y) , (Na, Mn) 15 Y 2 (CO 3 ) 9 (FSO 3 ) Cl.

From a chemical point of view, horváthite- (Y) can be used as a Y-dominant analogue to the Ce-dominated lukechangite- (Ce) , Na 3 Ce 2 (CO 3 ) 4 F, as a Na-dominant analogue to the Ca-dominated synchangite- (Y) , CaY (CO 3 ) 2 F, or e.g. B. as a Na-Y-dominant analogue to the Ba-Ce-dominated Kukharenkoite- (Ce) , Ba 2 Ce (CO 3 ) 3 F, to be understood.

Crystal structure

Crystal structure of horváthite- (Y) in cation-centered polyhedral representation and standard orientation. The blue outline shows the unit cell. Color legend: __ Na __ Y __ C __ O __ F

Horváthite- (Y) crystallizes in the orthorhombic crystal system in the space group Pmcn (space group no.62 , position 5) with the lattice parameters a = 6.964  Å , b = 9.173 Å and c = 6.302 Å as well as four formula units per unit cell . Template: room group / 62.5

The crystal structure of the horváthite (Y) contains two large cation positions: the seven-coordinate Na polyhedron and the eight-coordinate Y polyhedron. Each polyhedron can be described as a "bifurcated" octahedron , with the four shorter bonds to the F atoms describing the equatorial surface, while the longer cation-oxygen bonds form the axes of the octahedron. In the (Na-Φ 7 ) - "octahedron" only one oxygen tip (vertex) is "bifurcated", while in the (Y-Φ 8 ) - "octahedron" both oxygen tips have a "bifurcation". Horváthite- (Y) has a parallel (100) layered crystal structure, the two layers with NaY (CO 3 ) and F showing different compositions. Most REE fluorocarbonates are layered and have "upright" (CO 3 ) groups. The representatives of the Bastnäsit-Parisit-Röntgenit-Synchisit-Gruppe are based on syntactic intergrowths of different combinations of stacked rare earth elements, fluorine, alkali metals and carbonate groups. While there are two types of layers in the structure of, for example, bastnesite (Ce) with a CeF layer and a segregated layer of upright (CO 3 ) groups, horváthite (Y) and huanghoite (Ce) have baiyuneboite - (Ce) and lukechangite (Ce) - flat lying (CO 3 ) groups. In contrast to horváthite (Y), the structure of each of these minerals has (CO 3 ) layers that are separated from the layers with F, REE and alkali or alkaline earth metals . The structure of artificial BaCu (CO 3 ) F 2 with a Cu (CO 3 ) layer with flat (CO 3 ) groups and a BaF 2 layer, on the other hand, has features that also occur in the structure of Horváthite- (Y) .

properties

morphology

Horváthit- (Y) forms two different habitus variants. Mainly it is found in the form of isometric to elongated-blocky, columnar or fan-shaped aggregates up to 1.2 cm in length, which have a "cartwheel" -like or cylindrical habitus. These aggregates consist of sharp-edged, radially arranged, striped and according to [010] prismatic crystals from 1 mm to 5 mm long. The second habitus is formed from (100) thin tabular crystals about 1 × 1 × 0.25 mm in size, stacked in parallel on (100) (compare the crystal drawings on the right). The length of these crystals decreases continuously from the center of the stack outwards, so that this parallel intergrowth of many crystals looks like a grooved single crystal when viewed from the surface.

The costume of the horváthite (Y) crystals consists of the dominant front pinacoid {100}, the base pinacoid {001} and the side pinacoid {010} with {100}> {001}> {010}. Subordinate to the crystals are the prisms {110}, {011} and {101} (see also the adjacent crystal drawings).

physical and chemical properties

The crystals of Horváthit- (Y) are colorless to pale beige or pale pink. Their line color , however, is always white. The surfaces of the translucent to transparent crystals show a characteristic glass-like sheen . Horváthit- (Y) has a medium-high refraction ( n α  = 1.457; n β  = 1.543; n γ  = 1.622), but a very high birefringence (δ = 0.165) , corresponding to this glass gloss . In transmitted light, the biaxially negative horváthite (Y) is colorless to pale brown and has a weak pleochroism from Y  ≈  Z  = pale brown to X  = colorless.

Horváthit- (Y) has very good cleavage according to {100} and good cleavage according to {010}. Due to their brittleness , horváthite (Y) crystals break like amblygonite , with the break surfaces being uneven (irregular). Horváthit- (Y) has a Mohs hardness of 4 and is therefore one of the medium-hard minerals that can be easily scratched with a pocket knife, just as easily as the reference mineral fluorite (hardness 4). The measured density for horváthite- (Y) is 3.3 g / cm³, the calculated density is 3.61 g / cm³.

Horváthit- (Y) is not yet in the short wavelength in the long wavelength UV light , a fluorescent . The crystals of Horváthit- (Y) are already in weak organic acids like z. B. acetic acid , formic acid , citric acid or tartaric acid are potentially unstable.

Education and Locations

Horváthit- (Y) was found at its type locality in the vein-like, so-called “poudrette pegmatite” (or “poudrette dike”), which is the largest in the intrusive, alkaline, highly agpaitic gabbro-syenite complex of “Mont Saint-Hilaire “The pegmatite body found forms. It is a mineral that was formed late at low temperatures and is found in cavities in the hydrothermally modified peralkaline pegmatite. This crystallization stage favors the presence of cations with weak acid strength (weak acids), that is, cations with a low valence such as. B. Na + or cations with a large coordination number such. B. REE 3+ . During crystallization, weak Lewis acids are replaced by weak Lewis bases such as. B. F - and (CO 3 ) 2− stabilized. For this reason, REE fluorocarbonates such as. B. Horváthit- (Y). According to Horváth and Pfenninger-Horváth, horváthite (Y) is found as a mineral of the late phase in hydrothermally transformed zones of the Poudrette pegmatite.

The 1.5 to 2.0 m thick “Poudrette pegmatite dike” is located in the southeast corner of the “Poudrette Quarry” in the nepheline syenite. The area of ​​the pegmatite in which the Horváthite- (Y) was found is intensely altered. Many of the minerals identified along with horváthite- (Y) are intensely etched and corroded.

Typical accompanying minerals of Horváthit- (Y) in the cavities in the "Poudrette pegmatite" are microcline , Aegirin , dawsonite , rhodochrosite , sodalite , natrolite , albite , Serandit , siderite , Taeniolith , Katapleit , Astrophyllit , Genthelvin and a mineral of the Franconit group . In another area of ​​the same pegmatite dike, horváthite- (Y) is associated with "MSH UK-96" (identical to adamsite- (Y)), an alteration product of "MSH UK-96", sphalerite , rhodochrosite and microcline. As further parageneseminerals of Horváthit- (Y) are Gaidonnayit- , Donnayit- (Y) , Thomasclarkit- (Y) , Cryolite , Sabinait , Synchisit- (Ce) , Analcim , Gobbinsit , MSH UK-106 (identical to Adamsit- (Y) ), "MSH UK-107" (a still unwritten hydrous Na-Ca-Zr-Y-phosphate carbonate), "MSH UK-108" (a still unwritten hydrous Na-Ca-Y-phosphate carbonate) and petersenite (Ce) as well as Chabazit-Na and Leukophanit called.

As an extremely rare mineral formation, the horváthite (Y) has so far (as of 2019) only been described by three sites. The type locality for Horváthit- (Y) is the vein-shaped “Poudrette Dike” or “Poudrette pegmatite” exposed in the “Poudrette Quarry” in the alkaline rock Pluton of Mont Saint-Hilaire , Regional County Community of La Vallée-du-Richelieu , Montérégie , Québec , Canada . The relatively sparse type material, of which only a few milligrams exist, was recovered on the 7th level, but in 1997 and 1998 the same pegmatite provided additional, extensive material with horváthite- (Y) on the 8th level. The “Poudrette Quarry” also includes the quarries in the former “Demix Quarry”, which were sold to the Poudrette family in 1994 and into which the old “Desourdy Quarry” and “Uni-Mix Quarry” quarries had merged earlier. At the end of 2007, the Poudrette family sold the quarry, the name of which has since been given as “Carrière Mont Saint-Hilaire”.

The only other reference to Horváthit- (Y) is the storage aisle (Sill) of Saint-Amable in "Demix-Varennes Quarry" at Varennes and Saint-Amable , Regional County Municipality Marguerite-D'Youville (formerly Lajemmerais), Montérégie, Quebec, Canada.

Locations for Horváthit- (Y) from Germany , Austria and Switzerland are therefore unknown.

use

Horváthite- (Y) is only of interest to mineral collectors due to its rarity.

See also

literature

  • Joel D. Grice, George Yanji Chao: Horváthite- (Y), rare-earth-fluorocarbonate, a new mineral species from Mont Saint-Hilaire, Quebec . In: The Canadian Mineralogist . tape 35 , no. 3 , 1997, p. 743–749 (English, rruff.info [PDF; 1.7 MB ; accessed on April 8, 2019]).
  • László Horváth: Mineral Species discovered in Canada and species named after Canadians (The Canadian Mineralogist Special Publication 6) . 1st edition. Mineralogical Association of Canada, Ottawa 2003, ISBN 0-921294-40-9 , pp. 90 .
  • Horváthite- (Y) . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 67 kB ; accessed on April 8, 2019]).

Web links

Commons : Horváthite- (Y)  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d ALKALI-NUTS, Mont Saint-Hilaire - Mont Saint-Hilaire Unknowns. In: saint-hilaire.ca/msh. Retrieved March 13, 2019 .
  2. ↑ 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 ah ai aj ak al am an ao ap aq ar as at Joel D. Grice, George Yanji Chao: Horváthite- (Y), rare-earth-fluorocarbonate, a new mineral species from Mont Saint-Hilaire, Quebec . In: The Canadian Mineralogist . tape 35 , no. 3 , 1997, p. 743–749 (English, rruff.info [PDF; 1.7 MB ; accessed on April 8, 2019]).
  3. ↑ a b c d e f g Horváthite- (Y). In: mindat.org. Hudson Institute of Mineralogy, accessed April 8, 2019 .
  4. ↑ Horváthite- (Y) . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 67  kB ; accessed on April 8, 2019]).
  5. ↑ a b IMA / CNMNC List of Mineral Names; November 2018 (PDF 1.65 MB)
  6. ^ Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  299 .
  7. ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  8. ↑ a b c d e f g László Horváth, Elsa Pfenninger-Horváth: The minerals of Mont Saint-Hilaire . In: Lapis . tape 25 , no. 7/8 , 2000, pp. 23-59 .
  9. ↑ a b c Stefan Schorn and others: Horváthit- (Y). In: mineralienatlas.de. Retrieved April 8, 2019 .
  10. ^ László Horváth: Mineral Species discovered in Canada and species named after Canadians (The Canadian Mineralogist Special Publication 6) . 1st edition. Mineralogical Association of Canada, Ottawa 2003, ISBN 0-921294-40-9 , pp. 90 .
  11. ↑ N. Mercier, M. Leblanc: Existence of 3d transition metal fluorocarbonates: synthesis, characterization of BaM (CO 3 ) F 2 (M = Mn, Cu) and crystal structure of BaCu (CO 3 ) F 2 . In: European Journal of Solid State and Inorganic Chemistry . tape 30 , 1993, pp. 217-225 .
  12. ↑ Rudolf Duthaler, Stefan Weiß: Clean, prepare and store minerals. The workbook for the collector . 1st edition. Christian Weise Verlag, Munich 2008, ISBN 978-3-921656-70-9 , p. 154 .
  13. ↑ Localities for Horváthite- (Y). In: mindat.org. Hudson Institute of Mineralogy, accessed April 8, 2019 .
  14. ↑ Find location list for Horváthit- (Y) at the Mineralienatlas and at Mindat (accessed on April 8, 2019)
  15. ↑ Description of Poudrette Quarry. In: mindat.org. Hudson Institute of Mineralogy, accessed March 11, 2019 .
  16. ^ László Horváth, Elsa Horváth: An update of the minerals of the Saint-Amable sill . In: Canadian Micro-Mineral Association, Micronews . tape 51 , no. 9 , 2017, p. 2-4 .
  17. ↑ Description of Demix-Varennes quarry, Canada. In: mindat.org. Hudson Institute of Mineralogy, accessed April 8, 2019 .