Chlorkyuygenit

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Chlorkyuygenit
General and classification
other names

IMA 2012-046, kyygenite

chemical formula Ca 12 Al 14 O 32 [(H 2 O) 4 Cl 2 ]
Mineral class
(and possibly department) 		Silicates and Germanates
Similar minerals Fluoromayenite, chlormayenite, fluorocyuygenite
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic-hexakistrahedral; 4  3  m
Space group I 4 3 d (No. 220)Template: room group / 220
Lattice parameters a  = 12.0285 (natural)  Å
Formula units Z  = 2
Physical Properties
Mohs hardness 5 - 5.5
Density (g / cm 3 ) calculated: 2.941
Cleavage Please complete!
colour colorless, rarely pale green or yellow
Line color White
transparency transparent
shine Glass gloss
radioactivity -
magnetism -
Crystal optics
Refractive index n  = 1.672
Birefringence none, isotropic

The mineral Chlorkyuygenit is a rarely occurring oxide from the mayenite upper group with the idealized chemical composition Ca 12 Al 14 O 32 [(H 2 O) 4 Cl 2 ]. It crystallizes in the cubic crystal system with the structure of chloromayenite .

Chlorkyuygenit develops only very small, colorless crystals or rounded granules of less than 0.1 mm in size. The crystals show surfaces of the triakis tetrahedron {211}.

Chlorkyuygenit is formed at low pressure and high temperatures during the conversion of chloromayenite by a water-rich fluid .

Etymology and history

A cubic calcium aluminate has been known since the beginning of the 20th century, for which the composition 5CaO · 3Al 2 O 3 was given at the time. Since calcium aluminates are important compounds in cement clinker, they have been intensively studied since then.

The structure of this compound was elucidated in 1936 by W. Büssem and A. Eitel at the Kaiser Wilhelm Institute for Silicate Research in Berlin-Dahlem . In the course of the structure elucidation they corrected the composition to 12CaO · 7Al 2 O 3 , C 12 A 7 in the cement chemical notation .

The first finds of a natural, cubic calcium aluminate were made in 1963 by L. Heller in a Sprurrite rock in the Nalhal Ayalon outcrop of the Hatrurim Formation in Israel. It is a common mineral in many outcrops of the pyrometamorphic Hatrurim Formation.

A year later it was described as a new mineral by Gerhard Hentschel together with brownmillerite in limestone inclusions from lavas from Ettringer Bellerberg with the composition Ca 12 Al 14 O 33 . He named the new mineral after the nearby town of Mayen Mayenit .

The chlorine analog of mayenite, the compound 11CaO · 7Al 2 O 3  · CaCl 2 , was synthesized in 2008 by Tomoyuki Iwata and co-workers at the Nagoya Institute of Technology in Nagoya , Japan , and the structure was examined.

A hydrated chloromayenite from the ignimbrite of the Chengem Caldera in the North Caucasian Republic of Kabardino-Balkaria in Russia was described by Evgeni Galuskin and co-workers in 2013 and named Kyuygenite, after the location of the mountain Kyuygen-Kaya, as a new mineral by the CNMNC of the IMA accepted.

In the course of the redefinition of the Mayenite upper group since 2010, Mayenites from various sites were re-examined. All naturally occurring mayenites contain fluorine or chlorine and the composition given by Hentschel could not be confirmed in any case. Mayenite was then discarded as a mineral name, new minerals of the mayenite group were discovered and new names were introduced, including chlorinated kyuygenite for the kyuygenite from the Chengem caldera.

classification

In the current classification of the International Mineralogical Association (IMA), chlorinated cyuygenite belongs to the mayenite group with less than 4 Cl and 2 Si per formula unit together with chlormayenite , fluorkyuygenite and fluoromayenite in the mayenite upper group.

The outdated, but still in use 8th edition of the mineral classification according to Strunz does not list the chlorinated oxygenite. As a hydrated form of chloromayenite it would be part of the "Brownmillerite Mayenite Group" with the system no. IV / A.07 in the department of “Oxides and Hydroxides”.

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 know about chlorinated hydrogenite. Here he would with Mayenit in the unnamed group with the system no. 4.CC.20 in the department of "oxides (hydroxides, V [5,6] -vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)".

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , does not yet list the chlorinated oxygenite. Together with Mayenit he would be grouped in the unnamed group 11/07/03 of the department of "Multiple Oxides".

Chemism

Chlorocyuygenite with the idealized composition [X] Ca 12 [T] Al 3+ 14 O 32 [W] [(H 2 O) 4 Cl 2 ] is the chlorine analogue of fluorocyuygenite ( [X] Ca 12 [T] Al 3 + 14 O 32 [W] [(H 2 O) 4 F 2 ]) as well as the H 2 O analogue of chloromayenite ( [X] Ca 12 [T] Al 3+ 14 O 32 [W] [□ 4 Cl 2 ]), where [X], [T] and [W] are the positions in the mayenite structure and □ (blank) stands for an unoccupied grid position.

The composition from the type locality is

  • [X] Ca 11.979 [T] (Al 12.986 Fe 3+ 0.823 Si 0.179 Ti 0.033 ) O 32 [W] [(H 2 O) 3.767 Cl 2.234 (OH) 0.296 ]

The deviations from the ideal composition are essentially due to two rows of mixed crystals . On the one hand, Fe 3+ is incorporated in the [T] positions, corresponding to the exchange reaction

  • [T] Al 3+ = [T] Fe 3+ (hypothetical Fe analogue of chlorinated cyuygenite),

on the other hand, the mixed crystal formation with wadalite leads to low Si contents together with slightly increased contents of monovalent ions in the [W] position

  • [T] Al 3+ + [W] □ = [T] Si 4+ + [W] Cl - (wadalite)

The incorporation of OH groups, as in the case of chloromayenite or fluorocyuygenite, was not observed in the chlorocyuygenite from the type locality.

Crystal structure

Chlorkyuygenit crystallizes with cubic symmetry in the space group I 4 3 d (space group no. 220) with 2 formula units per unit cell . The natural mixed crystal from the type locality has the lattice parameter a  = 12.0285  Å . Template: room group / 220

The structure is that of chlormayenite . Aluminum (Al 3+ ) occupies the two tetrahedral Z-positions surrounded by 4 oxygen ions. They form a tetrahedral structure that encloses interconnected cages. Each of these cages is filled with two calcium (Ca 2+ ) ions, which are irregularly surrounded by 6 oxygen. In their center between the calcium ions, 1/3 of the cages contain a chlorine ion (Cl - ), the remaining 4 [W] positions contain H 2 O.

Education and Locations

Chlorkyuygenit forms contact metamorphic at low pressure and high temperatures during the hydration of chloromayenite by a water-rich fluid .

Chlorkyuygenit has so far (2018) only in its type locality , the skarn - xenoliths No. 1 from the ignimbrites of Mount Kyuygen-Kaya of the Chengem Caldera in the North Caucasian republic of Kabardino-Balkaria in Russia . It is found here as an inclusion in Chegemite , Reinhardbraunsite and Srebrodolskite or as a crust around Wadalite . More Begleitminerale are Fluorchegemit , Kumtyubeit , Rondorfit , Hydroxylellestadit , Lakargiit , perovskite , Kerimasit , Elbrusit , minerals of the ettringite group, Hydrocalumit , Bultfonteinit and Grossular - katoite - mixed crystals.

Web links

Individual evidence

  1. ↑ a b EV Galuskin, IO Galuskina, J. Kusz, T. Armbruster, R. Bailau, M. Dulski, VM Gazeev, NN Pertsev, AE Zadov and P. Dzierzanowski: Kyuygenite, IMA 2012-046. CNMNC Newsletter No. February 15, 2013, page 2 . In: Mineralogical Magazine . tape 77 , 2013, p. 1–12 ( cambridge.org [PDF; 126 kB ; accessed on August 5, 2018]).
  2. ↑ a b c d e f g h i j k l m n o p q r s t u v EV Galuskin, IO Galuskina, J. Kusz, F. Gfeller, T. Armbruster, R. Bailau, M. Dulski, VM Gazeev, NN Pertsev, AE Zadov, P. Dzierzanowski: Mayenite supergroup, part II: Chlorkyuygenite from northern Caucasus Kabardino-Balkaria, Russia, a new microporous mayenite supergroup mineral with `` zeolitic '' H2O. In: European Journal of Mineralogie . tape 27 , 2015, p. 123-136 , doi : 10.1127 / ejm / 2015 / 0027-2419 .
  3. ↑ Evgeny V. Galuskin, Frank Gfeller, Thomas Armbruster, Irina O. Galuskina, Yevgeny Vapnik, Mateusz Dulski, Mikhail Murashko, Piotr Dzierzanowsky, Viktor V. Sharygin, Sergey V. Krivovichev and Richard Wirth: Mayenite supergroup, part III: Fluormayenite, Ca12Al14O32 [ 〈4 F2], and Chlorkyuygenite, Ca12Al14O32 [(H2O) 4F2], two new minerals from pyrometamorphic rocks of the Hatrurim Complex, South Levant . In: European Journal of Mineralogie . tape 27 , 2015, p. 123-136 ( researchgate.net [PDF; 689 kB ; accessed on July 28, 2018]).
  4. ↑ Ernest Stanley Shepherd and GS Rankin: The binary systems of alumina with silica, lime, and magnesia; with optical study by Fred. Eugene Wright . In: American Journal of Science . tape 28 , 1909, pp. 293-333 , doi : 10.2475 / ajs.s4-28.166.293 .
  5. ↑ a b W. Büssem, A. Eitel: The structure of Pentacalciumtrialuminats . In: Journal of Crystallography . tape 95 , 1936, pp. 175–188 ( rruff.info [PDF; 628 kB ; accessed on July 22, 2018]).
  6. ^ S. Gross: The mineralogy of the Hatrurim formation, Israel. In: Geol. Surv. Isr. Bull. Band 70 , 1977, pp. 1–80 ( rruff.info [PDF; 5.7 MB ; accessed on July 29, 2018]).
  7. ↑ Michael Fleischer: New Mineral Names - Mayenite . In: The American Mineralogist . tape 50 , 1965, pp. 2096–2111 ( rruff.info [PDF; 1,3 MB ; accessed on July 29, 2018]).
  8. ↑ Tomoyuki Iwata, Masahide Haniuda, Koichiro Fukuda: Crystal structure of Ca12Al14O32Cl2 and luminescence properties of Ca12Al14O32Cl2: Eu2 + . In: Journal of Solid State Chemistry . tape 181 , 2008, p. 51-55 , doi : 10.1016 / j.jssc.2007.11.002 .
  9. ↑ a b c d Evgeny V. Galuskin, Frank Gfeller, Irina O. Galuskina, Thomas Armbruster, Radu Bailau and Viktor V. Sharygin: Mayenite supergroup, part I: Recommended nomenclature . In: European Journal of Mineralogie . tape 27 , 2014, p. 99–111 ( amazonaws.com [PDF; 802 kB ; accessed on June 30, 2018]).