Hydroxyferroroméit

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Hydroxyferroroméit
General and classification
other names

IMA 2016-006

chemical formula (Fe 2+ 1.5 □ 0.5 ) Sb 5+ 2 O 6 (OH)
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. according to Strunz 4.DH.15
Similar minerals Bindheimite
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fd 3 m (No. 227)Template: room group / 227
Lattice parameters a  = 10.25  Å
Formula units Z  = 8
Physical Properties
Mohs hardness ≈ 3
Density (g / cm 3 ) 5.453 (calculated)
Cleavage not specified
Break ; Tenacity shell-like
colour yellow to yellow-brown
Line color yellow
transparency translucent to opaque
shine Glass shine to earthy
Crystal optics
Refractive index n  = 1.898
Optical character isotropic

Hydroxyferroroméit is a rare mineral belonging to the mineral class of oxides and hydroxides . It crystallizes in the cubic crystal system with the composition (Fe 2+ 1.5 □ 0.5 ) Sb 5+ 2 O 6 (OH), so it is an iron - antimonate with additional hydroxide ions and a partially vacant A position.

Hydroxyferroroméit is found in the form of up to 50 µm large, powdery boxwork displacements according to tetrahedral , which are located in a siderite - quartz matrix. Its type locality is the prospectus "Correc d'en Llinassos" ("Ravin d'en Llinassous", Catalan Llinassos Brook ) ( coordinates of the prospectus Correc d'en Llinassos ) located 15 km north of the border with Spain near the village of Oms , Arrondissement Céret in the Occitania region in the Pyrénées-Orientales department , France .

Etymology and history

Due to the relative abundance of the mineral ullmannite in the small, at the turn of 19./20. The Oms siderite deposit, which was discovered in the 19th century and was mainly mined between 1937 and 1939, was investigated by the hobby miners Georges Favreau and Christian Berbain in the weathering zone of this deposit for rare nickel secondary minerals . This work led to the first detection of bottinoite in France as well as to the discovery of a light yellow mineral, which was first described in 2012 as Omsite (IMA 2012-025), Ni 2 Fe 3+ (OH) 6 [Sb (OH) 6 ]. Subsequently, a bindingheimite- like mineral was found in a lead-free zone of this deposit , in which a unique combination of elements was found after an energy-dispersive X-ray spectroscopic analysis , which suggested the presence of another new mineral.

After determining the physical, chemical and structural properties of the mineral from the prospectus “Correc d'en Llinassos”, it was submitted to the International Mineralogical Association (IMA), which recognized it in 2012 under the provisional designation IMA 2016-006 . The first scientific description of this mineral was made in 2017 by an international team of researchers including Stuart J. Mills , Andrew G. Christy , Mike S. Rumsey , John Spratt , Erica Bittarello , Georges Favreau , Marco E. Ciriotti and Christian Berbain in the European science magazine European Journal of Mineralogy . The authors named the mineral in accordance with the nomenclature of the pyrochlore upper group due to its chemical composition with an A position dominated by iron , a B position dominated by Sb and a Y position dominated by hydroxide ions as a hydroxyferroroméite ( English Hydroxyferroroméite ).

The type material for Hydroxyferroroméit is stored under the catalog number M53584 (holotype) in the collection of the Melbourne Museum "Museum Victoria" in Melbourne , Australia . Another level used for analyzes is located under the registration number BM2016,2 in the type mineral collection of the Natural History Museum in London , United Kingdom . The type grade of the Hydroxyferroroméit measures only 1.0 × 1.0 cm and, at the time of the first description, represented one of only two existing grades for this mineral.

Roméit was a mineral named in 1841 by Augustin Alexis Damour in honor of Jean-Baptiste Romé de L'Isle , French mineralogist and one of the founders of crystallography, which was discredited when the nomenclature of the pyrochlore upper group was redefined in 2010 because it hide behind its composition the new minerals fluoronatroroméite, fluorcalcioroméite and oxycalcioroméite. He is also the namesake for the Roméit sub-group within the pyrochlore upper group.

classification

The current classification of the International Mineralogical Association (IMA) counts the hydroxyferroroméit 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 Hydroxyferroroméit still Fluorcalciomikrolith , Fluornatromikrolith , Hydrokenomikrolith , Hydroxycalciomikrolith , Hydroxykenomikrolith , Kenoplumbomikrolith , Oxynatromikrolith , Oxystannomikrolith , Oxystibiomikrolith , Cesiokenopyrochlor , Fluorcalciopyrochlor , Fluornatropyrochlor , Hydrokenopyrochlor , Hydropyrochlor , Hydroxycalciopyrochlor , Hydroxykenopyrochlor , Hydroxymanganopyrochlor , Hydroxynatropyrochlor , Oxycalciopyrochlor , Fluorcalcioroméit , Hydroxycalcioroméit , Oxycalcioroméit , Oxyplumboroméite , Hydrokenoelsmoreit , Hydroxykenoelsmoreit , Fluornatrocoulsellit and Hydrokenoralstonit . Hydroxyferroroméite forms together with fluorcalcioroméite, hydroxycalcioroméite (formerly Lewisite), oxycalcioroméite and oxyplumboroméite within the pyrochlore upper group the Roméite group .

The 8th edition of the mineral classification according to Strunz , which is now outdated, but still in use in some cases, does not yet list the hydroxyferroroméit.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), does not yet know the hydroxyferroroméit either. It would be classified in the department of "oxides with the molar ratio metal: oxygen = 1: 2 and comparable". This is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral is classified according to its composition and structure in the subsection “With large (± medium-sized) cations; Layers of edge-linked octahedra ”would 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 would form. Would Hydroxyferroroméit thereby together with Fluorcalcioroméit, Fluornatroroméit , Hydroxycalcioroméit (formerly Lewisite ) Oxycalcioroméit, Oxyplumboroméite (formerly Bindheimite ) Bismutostibiconit (Q), Monimolit (Q), Partzit (Q), Stetefeldtit (Q) and Stibiconit (Q) in the Roméitgruppe to find.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , does not yet know the hydroxyferroroméit.

Chemism

Nine microprobe analyzes on hydroxyferroroméite grains from the type locality gave mean values ​​of 67.10% Sb 2 O 5 ; 0.15% As 2 O 5 ; 1.17% SiO 2 ; 0.28% Al 2 O 3 ; 0.18% CaO; 0.58% SrO; 16.95% FeO; 8.69% CuO; 0.54% ZnO; 1.72% H 2 O (calculated from the stoichiometry) and sum = 97.36%. The valence of Fe, Cu and Sb in hydroxyferroroméite was determined by X-ray photoelectron spectroscopy (XPS); thereafter the oxidation numbers for iron and copper are +2 and for antimony +5. H 2 O was determined on the basis of 7 (O + OH + H 2 O). On the basis of seven (O + OH) per formula unit, the chemical analysis for Hydroxyferroroméit resulted in the empirical formula (Fe 2+ 1.07 Cu 2+ 0.50 Zn 0.03 Sr 0.03 Ca 0.01 □ 0, 36 ) Σ = 2.00 (Sb 5+ 1.88 Si 0.09 Al 0.02 As 0.01 ) Σ = 2.00 O 6 ((OH) 0.86 O 0.14 ) calculated to be (Fe 2+ 1.5 □ 0.5 ) Sb 5+ 2 O 6 (OH) has been simplified and contents of 24.48% FeO, 73.48% Sb 2 O 5 and 2.05% H 2 O (total 100.00%).

Hydroxyferroroméit is next to the insufficiently characterized flajolotite , 4FeSbO 4 3H 2 O (?), The only mineral with the element combination Fe - Sb - H - O. Schafarzikite , Fe 2+ Sb 3+ 2 O 4 , tripuhyite , Fe are chemically similar 3+ Sb 5+ O 4 , chapmanite , Fe 3+ 2 Sb 3+ (Si 2 O 5 ) O 3 (OH), derbylite , Fe 3+ 4 Ti 3 Sb 3+ O 13 (OH), hemloite , (Ti , V 3+ , Fe 3+ , Al) 12 (As 3+ , Sb 3+ ) 2 O 23 (OH), Omsite, Ni 2 Fe 3+ (OH) 6 [Sb (OH) 6 ], Örebroite , Mn 2+ 3 (Sb 5+ , Fe 3+ ) (SiO 4 ) (O, OH) 3 , rinmanite , Zn 2 Sb 2 Mg 2 Fe 4 O 14 (OH) 2 , and whitecapsite , H 16 Fe 2+ 5 Fe 3+ 14 Sb 3+ 6 (AsO 4 ) 18 O 16 · 120H 2 O.

Within the pyrochlore upper group there are theoretically a multitude of substitution possibilities due to the four different positions to be occupied, but there is currently only one analogue. Within the Roméite group, hydroxyferroroméite is the Fe-dominant analogue of the Ca-dominated hydroxycalcioroméite. Hydroxyferroroméite is the first mineral of the Roméite group (and also of the entire pyrochlore upper group) with a predominance of Fe 2+ on the A position, while all other representatives of the Roméite group are either Ca or Pb dominant.

Crystal structure

Hydroxyferroroméit crystallizes in the cubic crystal system in the space group Fd 3 m (space group no. 227) with the lattice parameter a = 10.25  Å and eight formula units per unit cell . Template: room group / 227

In the crystal structure of the form Hydroxyferroroméits SbO 6 - octahedron corner sharing a characteristic for representatives of the pyrochlore supergroup B 2 X 6 scaffold. The A positions are 75% Fe 2+ occupied. The Y positions are completely occupied by oxygen , which is bound to hydrogen atoms that are distributed over partially occupied positions. Stuart Mills and colleagues assume a four-fold disorder of the H-positions, which is ensured locally by an order in the close range. Each oxygen atom in a Y position would be bound to a hydrogen atom and three iron atoms in an approximately tetrahedral configuration.

properties

morphology

Hydroxyferroroméit was only found at its type locality in the form of powdery, yellow boxwork displacements according to tetrahedrite at maximum 50 µm in size . The corridors within the boxwork (cassette work) itself were in turn replaced by a more glassy, ​​yellow-brown variety of hydroxyferroroméits. Discrete crystals have not yet been identified.

physical and chemical properties

The aggregates of the Hydroxyferroroméits are yellow to yellow-brown, while their line color is always yellow. The surfaces of the translucent to opaque Hydroxyferroroméits are earthy or have a glass-like sheen , which corresponds very well with the moderately high value for the refraction of light (n = 1.898). Hydroxyferroroméit, because it belongs to the cubic crystal system, has no birefringence and is optically completely isotropic.

Since no crystals were detected for Hydroxyferroroméit, there is no information on cleavage . The mineral breaks in a similar way to quartz , with the fracture surfaces having a shell-like shape. With a Mohs hardness of ≈ 3, the mineral is one of the medium-hard minerals and, like the reference mineral calcite, can be scratched with a copper coin. Discrete crystals with an assumed Mohs hardness of 5.5, which is comparable to hydroxycalcioroméite, are likely to be significantly harder. The calculated density is 5.453 g / cm³.

There is no information on possible fluorescence in short or long wave UV light , as well as information on chemical behavior.

Education and Locations

Hydroxyferroroméit was found in a boxwork (cassette work) which formed when tetrahedrite was displaced under mildly acidic and oxidizing conditions.

Typical accompanying minerals of the hydroxyferrorome in its type material are the matrix-forming minerals siderite and quartz as well as hematite , goethite , tetrahedrite, chalcopyrite and native antimony , which are at least partly remnants of the primary ore minerals . In the "Australian Broken Hill Consols Mine" (see below) the mineral was encountered together with chlorargyrite and dyscrasite .

As a very rare mineral formation, the hydroxyferroroméite could only be described from two sources so far (status 2018). The type locality for Hydroxyferroroméit is the prospectus "Correc d'en Llinassos" (Ravin d'en Llinassous) located 15 km north of the border with Spain near the village Oms in the Arrondissement Céret in the region Occitania , Département Pyrénées-Orientales , France . The only other point of discovery is the "Australian Broken Hill Consols Mine" (Consols Lode) near Broken Hill in the mining district of the same name, Yancowinna County, New South Wales , Australia.

Sites for Hydroxycalcioroméit in Germany , Austria and Switzerland are therefore unknown.

See also

literature

  • Stuart J. Mills, Andrew G. Christy, Mike S. Rumsey, John Spratt, Erica Bittarello, Georges Favreau, Marco E. Ciriotti, Christian Berbain: Hydroxyferroroméite, a new secondary weathering mineral from Oms, France . In: European Journal of Mineralogy . tape 29 , no. 2 , 2017, p. 307–314 , doi : 10.1127 / ejm / 2017 / 0029-2594 (English).

Web links

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 Stuart J. Mills, Andrew G. Christy, Mike S. Rumsey, John Spratt, Erica Bittarello , Georges Favreau, Marco E. Ciriotti, Christian Berbain: Hydroxyferroroméite, a new secondary weathering mineral from Oms, France . In: European Journal of Mineralogy . tape 29 , no. 2 , 2017, p. 307–314 , doi : 10.1127 / ejm / 2017 / 0029-2594 (English).
  2. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2020, accessed May 2, 2020 .
  3. ↑ a b Mineralienatlas: Hydroxyferroroméit
  4. ↑ a b c d e Hydroxyferroroméite. In: mindat.org. Hudson Institute of Mineralogy, accessed September 12, 2019 .
  5. ↑ Stuart J. Mills, Anthony R. Kampf, Robert M. Housley, Georges Favreau, Marco Pasero, Cristian Biagioni, Stefano Merlino, Christian Berbain, Paolo Orlandi: Omsite, (Ni, Cu) 2 Fe 3+ (OH) 6 [ Sb (OH) 6 ], a new member of the cualstibite group from Oms, France . In: Mineralogical Magazine . tape 76 , no. 5 , 2012, p. 1347–1354 , doi : 10.1180 / minmag.2012.076.5.16 (English, researchgate.net [PDF; 1.5 MB ; accessed on May 2, 2020]).
  6. ^ A b c 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 September 11, 2019]).
  7. ^ 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, cnmnc.main.jp [PDF; 85 kB ; accessed on September 11, 2019]).
  8. ^ Franz Eugen Hussak, George Thurland Prior: Lewisite and zirkelite, two new Brazilian minerals . In: Mineralogical Magazine . tape 11 , 1895, p. 80–88 , doi : 10.1180 / minmag.1895.011.50.05 (English, rruff.info [PDF; 331 kB ; accessed on September 11, 2019]).
  9. ↑ Natalia V. Zubkova, Dmitry Yu. Pushcharovsky, Daniel Atencio, Alla V. Arakcheeva, Paulo Anselmo Matioli: The crystal structure of lewisite, (Ca, Sb 3+ , Fe 3+ , Al, Na, Mn, □) 2 (Sb 5+ , Ti) 2 O 6 (OH) . In: Journal of Alloys and Compounds . tape 296 , no. 1-2 , 2000, pp. 562-569 , doi : 10.1016 / S0925-8388 (99) 00513-7 (English).
  10. ↑ Localities for Hydroxyferroroméite. In: mindat.org. Hudson Institute of Mineralogy, accessed September 12, 2019 .
  11. ↑ Find location list for Hydroxyferroroméite at the Mineralienatlas and at Mindat (accessed on November 25, 2018)