Hydroxymanganopyrochlore

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Hydroxymanganopyrochlore
General and classification
chemical formula (Mn 2+ , Th, Na, Ca, REE) 2 (Nb, Ti) 2 O 6 (OH)
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)Template: room group / 227
Lattice parameters a  = 10.2523  Å
Formula units Z  = 8
Frequent crystal faces {111}
Physical Properties
Mohs hardness not specified
Density (g / cm 3 ) 5,398 (calculated)
Cleavage no
Break ; Tenacity not specified; brittle
colour dark brown, black
Line color not specified, probably light brown
transparency not specified
shine not specified
Crystal optics
Refractive index n  = 2.29 (calculated)
Optical character isotropic

Hydroxymanganopyrochlore is a very rare mineral from the mineral class of oxides and hydroxides . It crystallizes in the cubic crystal system with the composition (Mn 2+ , Th, Na, Ca, REE) 2 (Nb, Ti) 2 O 6 (OH), so it is a manganese - thorium - calcium - rare earth - niobate with additional hydroxide ions .

Hydroxymanganopyrochlore occurs at its type locality in octahedral crystals with a maximum size of 0.7 mm, which sit in miarolithic cavities in the sanidinite. The type locality of Hydroxymanganopyrochlors are 1.5 km northeast of Mendig lying pumice "In the dents" (pit "Zieglowski") at Niedermendig ( coordinates of the quarries "In the dents" ), Laacher See complex , Eifel , Rheinland-Pfalz , Germany .

Etymology and history

In the material from a find by Günter Blass some time ago, octahedral crystals were identified, which could be addressed as pyrochlore , but their preliminary analysis data prevented a classification into the old nomenclature of the pyrochlore group according to Donald David Hogarth and colleagues. Only more recent analyzes by Russian mineralogists led to the proof of the presence of a new representative of the current pyrochlore upper group. The new mineral was presented to the International Mineralogical Association (IMA), which recognized it in 2012 under the tentative designation IMA 2012-005 . The first scientific description of this mineral took place in 1979 by a Russian-German research team with Nikita V. Chukanov , Günter Blass , Natalia V. Zubkova , Igor V. Pekov , Dmitry Yu. Pushcharovskii and Heribert Prinz . The authors named the new mineral in accordance with the nomenclature of the pyrochlore upper group due to the chemical composition of the mineral with an A position dominated by manganese , B position dominated by Nb and Y position dominated by OH as hydroxymanganopyrochlor ( English: hydroxymanganopyrochloride ).

The type material for hydroxymanganopyrochlore is kept under the catalog number 4226/1 in the systematic collection of the Mineralogical Museum " Alexander Evgenjewitsch Fersman " of the Russian Academy of Sciences in Moscow .

Pyrochlore was originally found by Nils Otto Tank (1800–1864) near Stavern in the Norwegian province of Vestfold and described in 1826 by Friedrich Wöhler . Wöhler named the mineral based on a suggestion by Jöns Jakob Berzelius after the Greek words πῦς [ pyr ] and χλωρός [ chlorós ] for "fire" and "green" because of its property, after melting with phosphorus salt (sodium ammonium hydrogen phosphate) before Solder tube to solidify to a grass-green glass. Over the decades, the term pyrochlore has often been used unspecifically and often without the background of chemical analysis. The mineral pyrochlore was discredited in 2010.

classification

The current classification of the International Mineralogical Association (IMA) counts the hydroxymanganopyrochlore 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 Hydroxymanganopyrochlor still Fluorcalciomikrolith , Fluornatromikrolith , Hydrokenomikrolith , Hydroxycalciomikrolith , Hydroxykenomikrolith , Kenoplumbomikrolith , Oxynatromikrolith , Oxystannomikrolith , Oxystibiomikrolith , Cesiokenopyrochlor , Fluorcalciopyrochlor , Fluornatropyrochlor , Hydrokenopyrochlor , Hydropyrochlor , Hydroxycalciopyrochlor , Hydroxykenopyrochlor , Hydroxynatropyrochlor , Oxycalciopyrochlor , Fluorcalcioroméit , Hydroxycalcioroméit , Hydroxyferroroméit , Oxycalcioroméit , Oxyplumboroméite , Hydrokenoelsmoreit , Hydroxykenoelsmoreit , Fluornatrocoulsellit and Hydrokenoralstonit . Hydroxymanganopyrochlor together with Cesiokenopyrochlor, Fluorcalciopyrochlor, Fluornatropyrochl, Hydrokenopyrochl, Hydropyrochl, Hydroxycalciopyrochlor, Hydroxykenopyrochl, Hydroxynatropyrochlor and Oxycalciopyrochlor within the pyrochlore upper group the pyrochlore 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 hydroxymanganopyrochlore. 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), also does not yet recognize hydroxymanganopyrochlore. 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. Hydroxymanganopyrochlor would be doing with Fluorcalciopyrochlor , Fluornatropyrochlor , Fluorkenopyrochlor , Fluorstrontiopyrochlor , Hydropyrochlor (formerly Kalipyrochlor ) Hydroxycalciopyrochlor , Kenoplumbopyrochlor , Oxycalciopyrochlor (formerly Stibiobetafit ) Oxynatropyrochlor , Oxyplumbopyrochlor and Oxyyttropyrochlor- (Y) found in the Pyrochlorgruppe.

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

Seven analysis with the electron - microprobe at a Hydroxymanganopyrochlor-crystal of the type locality provided average values of 2.48% Na 2 O; 3.65% CaO; 8.22% MnO; 3.39% Fe 2 O 3 ; 3.22 La 2 O 3 ; 6.76 Ce 2 O 3 ; 0.92 Nd 2 O 3 ; 15.43% TiO 2 ; 22.58% ThO 2 ; 2.42 UO 2 ; 29.42% Nb 2 O 5 ; 0.49% F 2 ; 1.34% H 2 O (calculated) and [(-O ≡ F 2 ) -0.21%, sum = 100.11%]. On the basis of seven anions (O, OH, F) per formula unit, the empirical formula (Mn 0.51 Th 0.37 Na 0.35 Ca 0.29 Ce 0.18 La 0.09 Nd 0.02 U 0.04 ) Σ = 1.85 (Nb 0.97 Ti 0.85 Fe 3+ 0.19 ) Σ = 2.01 O 6 [(OH) 0.65 O 0.24 F 0.11 ] determined, which can be simplified to (Mn 2+ , Th, Na, Ca, REE) 2 (Nb, Ti) 2 O 6 (OH), which also corresponds to the official notation of the IMA for the formula of hydroxymanganopyrochloride.

In addition to hydroxymanganopyrochloride, peterandresenite , Mn 4 Nb 6 O 19 · 14H 2 O, is the only mineral with the element combination “Mn - Nb - O - H”. Chemically similar to hydroxymanganopyrochlore are a number of minerals, such as B. Gerasimovskite , (Mn, Ca) (Nb, Ti) 5 O 12 · 9H 2 O, and manganese lyanite , (Mn, Ca) (Ti, Nb) 5 O 12 · 9H 2 O

Within the pyrochlore upper group there are theoretically a multitude of substitution possibilities due to the four different positions to be occupied. Hydroxymanganopyrochlore is the Mn-dominant analogue of Ca-dominated hydroxycalciopyrochloride, vacancy-dominated hydroxykenopyrochloride and Na-dominated hydroxynatropyrochloride. Across all subgroups, there are no representatives of the pyrochlore upper group with Mn dominance in the A position. However, Uwe Kolitsch and colleagues mention a Ca-, Y- and Ti-rich Sb analogue of hydroxymanganopyrochlore, which would be called hydroxymanganoroméite according to the appropriate description and recognition by the IMA .

Crystal structure

Hydroxymanganopyrochlor crystallizes in the cubic crystal system in the space group Fd 3 m (space group no. 227) with the lattice parameter a = 10.2523  Å and eight formula units per unit cell . Template: room group / 227

As consisting of all representatives of the pyrochlore group Upper crystal structure of Hydroxymanganopyrochlor from B O 6 - octahedra - in this case, (Nb, Ti) O 6 octahedra - with shared corners, which form a scaffold. In this framework, the A cations (Mn 2+ , Th, Na, Ca, REE) sit in the center of “Thomson cubes”, with Mn being the dominant cation. Due to the incorporation of Mn 2+ on the A - and the high Ti content on the B - position, hydroxymanganopyrochlore is characterized by low values ​​for the lattice parameter "a" compared with other members of the pyrochlore upper group. Due to this fact, but especially due to the high thorium content, hydroxymanganopyrochlore has a significantly higher density than its calcium-dominant analogue.

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

properties

Drawing of an octahedral hydroxymanganopyrochlore crystal

morphology

At its type locality, hydroxymanganopyrochlore forms idiomorphic crystals with a maximum size of 0.7 mm, whose costume consists exclusively of the octahedron (see the crystal drawing on the right).

physical and chemical properties

The crystals of hydroxymanganopyrochloride are dark brown to black with red reflections at their type locality. There is no information about their line color - the color of the mineral powder is likely to be a pale light brown. There is also no information on the luster of the mineral, which due to the very high calculated value for light refraction (n = 2.29) is likely to be resinous to diamond-like. Hydroxymanganopyrochlore is optically isotropic.

The mineral has no cleavage properties . Due to its brittleness , however , it breaks in a characteristic way, with no information on the formation of the break surfaces. The Mohs hardness of hydroxymanganopyrochloride is unknown, but should be between 4 and 5 in analogy to the other representatives of the pyrochlore upper group. The calculated density for hydroxymanganopyrochlore is 5.398 g / cm³.

There is no information on fluorescence in UV light or on cathodoluminescence under the electron beam for the mineral, as well as information on chemical behavior.

In contrast to most of the other representatives of the pyrochlore upper group with high concentrations of uranium and thorium, hydroxymanganopyrochlore is not metamictic , which is due to its lower geological age (the last eruption in the Laacher See complex took place around 13,000 years ago).

Education and Locations

Hydroxymanganopyrochlore is a late pneumatolytic formation. His accompanying minerals include sanidine , Nosean , biotite , Tephroit , Jakobsit and spinels of Gahnit - Hercynit - solid solutions that are all in miarolithischen cavities in Sanidinit.

At the time of the first description, only three crystals of hydroxymanganopyrochlore were known. As an extremely rare mineral formation, hydroxymanganopyrochlore could only be described worldwide by its type locality (as of 2018). The type locality for Hydroxymanganopyrochlor are the 1.5 km northeast of Mendig lying pumice quarries "In the dents" (pit "Zieglowski") at Niedermendig in Laacher Lake complex , Eifel , Rhineland-Palatinate , Germany .

use

Hydroxymanganopyrochlor would be due to its Nb 2 O 5 -contents 28.92 to 30.63 wt .-% a rich niobium - ore . Due to its rarity, however, the mineral is of no practical importance and only of interest to mineral collectors.

See also

literature

  • Nikita V. Chukanov, Günter Blass, Natalia V. Zubkova, Igor V. Pekov, Dmitry Yu. Pushcharovskii, Heribert Prinz: Hydroxymanganopyrochlore: A New Mineral from the Eifel Volcanic Region, Germany . In: Doklady Earth Sciences . tape 449 , no. 1 , 2013, p. 342-345 , doi : 10.1134 / S1028334X13030100 (English).
  • Hydroxymangano pyrochloride . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.com [PDF; 117 kB ; accessed on October 8, 2018]).

Web links

Commons : Hydroxymanganopyrochlore  - Collection of pictures, videos and audio files

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 Nikita V. Chukanov, Günter Blass, Natalia V. Zubkova, Igor V. Pekov, Dmitry Yu. Pushcharovskii, Heribert Prinz: Hydroxymanganopyrochlore: A New Mineral from the Eifel Volcanic Region, Germany . In: Doklady Earth Sciences . tape 449 , no. 1 , 2013, p. 342-345 , doi : 10.1134 / S1028334X13030100 (English).
  2. ^ 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]).
  3. ↑ a b Günter Blaß, Fred Kruijen: The new mineral finds from the Vulkaneifel . In: Mineral World . tape 23 , no. 5 , 2012, p. 38-48 .
  4. ↑ a b c d 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. ↑ a b Friedrich Wöhler: About the pyrochlore, a new mineral species . In: Poggendorff's annals of physics and chemistry . tape 7 , no. 4 , 1826, pp. 417-428 ( limited preview in Google Book search).
  6. ^ 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]).
  7. ^ IMA / CNMNC List of Mineral Names; March 2018 (PDF 1.65 MB)
  8. ↑ a b Mindat - Hydroxymanganopyrochlore , accessed on October 8, 2018 (English)
  9. ↑ Yang Guangming, Li Guowu, Xiong Ming, Pan Baoming, Yan Chenjie: Hydroxycalciopyrochlore, a new mineral species from Sichuan, China . In: Acta Geologica Sinica (english edition) . tape 88 , no. 3 , 2014, p. 748-753 , doi : 10.1111 / 1755-6724.12235 (English).
  10. ↑ Ritsuro Miyawaki, Koichi Momma, Satoshi Matsubara, Takashi Sano, Masako Shigeoka, Hiroyuki Horiuchi: Hydroxykenopyrochlore, IMA 2017-030a. CNMNC Newsletter No. 39, October 2017, page 1285 . In: Mineralogical Magazine . tape 81 , 2017, p. 1279-1286 (English).
  11. ↑ 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).
  12. ↑ Uwe Kolitsch, Tobias Schachinger, Christian Auer: aegirine, aegirine-augite, albite, baddeleyite, barite, brandtite (?), Braunite, calcite, canosioite, clinosuenoite (formerly "manganocummingtonite"), celestin, diaspore, dolomite, fluorapatite (As -containing), Fluorcalcioroméit, Gamagarit, Hematite, Hausmannite, Hjalmarit, Hollandite, Hydroxycalcioroméite, Clinochlor, Kutnohorite, mixed crystals Manganiandrosite- (La) - Manganiakasakait- (La), Nambulite, Phlogopite, Piemontigerite, Pyrobelite, Pyrobium Ranciéite (?), Rhodochrosite, rhodonite, richterite, rutile, spessartine, talc, thorite, tremolite, tilasite, titanite, tokyoite, wakefieldite (Ce), wakefieldite (Y), zircon, the Sb analog of hydroxymanganopyrochlore and unnamed LaAsO 4 from Obernberger Tribulaun, North Tyrol - a first report on mineralogically complex, lens-shaped metamorphic manganese mineralization . In: Carinthia II . tape 208/128 , 2018, p. 206-213 .
  13. ↑ Mindat - Number of locations for Hydroxymanganopyrochlore , accessed on October 8, 2018 (English)
  14. ↑ List of locations for hydroxymanganopyrochlore from the Mineralienatlas and Mindat (accessed on October 8, 2018)