Wadalite

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Wadalite
Wadalite.jpg
Yellow wadalite crystals from Ettringer Bellerberg , Eifel, Rhineland-Palatinate, Germany
General and classification
chemical formula Ca 12 Al 10 3+ Si 4 O 32 Cl 6
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.AD.25 ( 8th edition : VIII / A.08)
04.51.05.01
Similar minerals Grossular , hydrogrossular
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  = natural: 12.001, synthetic: 11.981  Å
Formula units Z  = 2
Frequent crystal faces Triacistrahedron {211}
Physical Properties
Mohs hardness 6.5
Density (g / cm 3 ) measured: 3.01; calculated: 3.056
Cleavage not observed
colour colorless, yellow, dark gray to black
Line color White
transparency transparent to translucent
shine Glass gloss
radioactivity no
Crystal optics
Refractive index n  = 1.708, 1.712
Birefringence none, as isotropic

The mineral wadalite is a rarely occurring island silicate from the mayenite upper group with the idealized chemical composition Ca 12 Al 10 3+ Si 4 O 32 Cl 6 . It crystallizes in the cubic crystal system with the structure of mayenite .

Wadalite is transparent to translucent and develops only small, glass- glossy , dark gray to black or colorless to lime yellow crystals of up to one mm in size. The crystal form is dominated by the triakis tetrahedron {211}.

Wadalite is formed in contact metamorphosis at low pressure and very high temperatures during the sanidinite facial metamorphosis of rocks rich in calcium and aluminum and is mainly found in skarn inclusions in igneous rocks .

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 determination, they corrected the composition to 12CaO · 7Al 2 O 3 .

The synthetic equivalent of wadalite, a chlorosilicate with the structure of 12CaO 7Al 2 O 3 determined by Büssem and Eitel , was described in 1988, before Tsukimura and co-workers found the mineral wadalite in a skarn xenolite of an andesite near Tadano near Kōriyama in five years later in Fukushima Prefecture , Japan . They described the structure in analogy to the garnet structure and wadalite was therefore long assigned to the garnet group . Wadalit was named after the Japanese mineralogist Tsunashiro Wada , the first general director of the Geological Survey of Japan, who had made a contribution to modern mineralogy in Japan.

In 1995, Glasser once again highlighted the differences between the structures of wadalite and garnet and current classifications classify garnet and wadalite in different mineral groups .

In the following years more minerals with the structure of mayenite were found and the group and mineral definitions were revised by EV Galuskina and co-workers.

classification

The current classification of the International Mineralogical Association (IMA) counts wadalite to the mayenite upper group, where together with adrianite and its Fe 3+ analog Eltyubyuit it forms the wadalite group with more than 4 Cl and 2 Si per formula unit.

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the wadalite was counted because of its structural similarity to the garnet to the division of the "island silicates (nesosilicates)", where it together with almandine , andradite , calderite , goldmanite , grossular , henritermierite , Hibschite , Holtstamit , Hydrougrandit , katoite , Kimzeyit , Knorringit , majorite , Morimotoit , Pyrop , Schorlomit , Spessartin , Uwarowit and Yamatoit (discredited because identical to Momoiit ) the "garnet group" with the system number. VIII / A.08 .

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 classifies wadalite under the category of "island silicates (nesosilicates)". This is further subdivided according to the possible presence of further anions and the coordination of the cations involved , so that the mineral is classified according to its composition in the subsection “Island silicates without additional anions; Cations in octahedral [6] and usually greater coordination “can be found, where it is found together with almandine, andradite, calderite, goldmanite, grossular, henritermierite, hibschite, holtstamite, katoite, kimzeyite, knorringite, majorite, morimotoite, pyrope, schorlomite , Spessartin, and Uwarowit as well as the now discredited minerals Blythite, Hydroandradite and Skiagite the "garnet group" with the system no. 9.AD.25 forms.

The systematics of minerals according to Dana , which is predominantly used in the English-speaking area , also classifies wadalite in the “island silicate minerals ” department. Within the sub-section "[[Systematics of minerals according to Dana / Silicates # 51.04 Island silicates: SiO4 groups only with cations in [6] and> [6] coordination | Island silicates: SiO 4 groups only with cations in [6] and> [6] -coordination]] “it is the only mineral in the unnamed group 51.04.05 with the system number 51.04.05.01 .

Chemism

Wadalite with the idealized composition [X] Ca 12 [T] (Al 10 3+ Si 4 ) O 32 [W] Cl 6 is the silicon - chlorine analog of chloromayenite ( [X] Ca 12 [T] Al 14 3+ O 32 [W] [Cl 2 □ 4 ]), where [X], [T] and [W] are the positions in the mayenite structure.

The composition of the sector-zoned crystals from the type locality differs slightly in the sectors:

  • {21-1}: [X] Ca 12.01 [T] (Al 3+ 7.88 Fe 3+ 0.99 Si 4.51 Ti 0.05 Mg 0.56 ) O 32.22 [W] Cl 5, 55
  • {211}: [X] Ca 12.05 [T] (Al 3+ 8.42 Fe 3+ 0.85 Si 4.20 Ti 0.04 Mg 0.44 ) O 32.19 [W] Cl 5.38

The deficit of Cl indicates the formation of mixed crystals with chloromayenite, corresponding to the exchange reaction

  • [T] Si 4+ + [W] Cl - = [T] Al 3+ + [W] □, (chloromayenite, □: blank).

The Fe 3+ contents are the admixture of Eltyubyuit according to the exchange reaction

  • [T] Al 3+ = [T] Fe 3+ (Eltyubyuit)

and the magnesium contents together with the excess of silicon (Si) are based on mixed crystal formation with the Mg-Si analogue adrianite ( [X] Ca 12 [T] (Mg 5 2+ Si 4+ 9 ) O 32 [W] Cl - 6 ) according to the exchange reaction

  • 2 [T] Al 3+ = [T] Mg 2+ + [T] Si 4+

A mixed crystal with a high adrianite content ( [X] Ca 12 [T] (Al 3+ 4 Mg 3 2+ Si 4+ 7 ) O 32 [W] Cl - 6 ) was detected in the Allende meteorite.

Crystal structure

Wadalite 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  = 12.001  Å . For synthetic wadalite a  = 11.981 Å was measured. Template: room group / 220

The structure is that of chlormayenite . Aluminum (Al 3+ ) and silicon (Si 4+ ) occupy the Z positions, which are tetrahedrally 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, the cages contain a chlorine ion (Cl - )

Education and Locations

Wadalite forms contact metamorphic in skarns at low pressure and high temperatures during the conversion of calcium-aluminum-silicates by a chlorine-rich fluid . Other deposits are lime silicate clinker from spent coal heaps and calcium-aluminum inclusions in chondrites .

Skarne

The type locality of wadalite is a contact metamorphic skarn inclusion ( xenolite ) from an andesite near Tadano near Kōriyama in the prefecture of Fukushima , Japan . Wadalite is found here together with wollastonite , calcite , katoite , andradite , thaumasite , tobermorite and xonotlite in the edge area of ​​the xenolites, on the border to the core of nominally anhydrous minerals (wollastonite, grossular, andradite, gehlenite and hydroxylapatite - hydroxylellestadite - mixed crystals). Wadalite was formed here when gehlenite reacted with a chlorine-rich fluid. The sector zoning indicates rapid crystal growth far from chemical equilibrium. Retrograde, wadalite was converted to katoite from the edge and along cracks.

In the La Negra mine near Maconi at Cadereyta in the state of Querétaro , Mexico wadalite occurs in the contact area of a diorite with limestone together with spurrite and Rustumit and was partially converted into hydrogrossular.

In xenoliths of leucite - Tephrits from Bellerberg volcano in Ettringen and Mayen in the Eifel in Rhineland-Palatinate , Germany , iron-rich wadalite shall meet with gehlenite, Cuspidin , ellestadite , fluorite , ettringite , gypsum and Reinhardbraunsit on.

Further occurrences in Skarnen are the calcium silicate xenolites from the Chegem Caldera in the North Caucasian Republic of Kabardino-Balkaria in Russia .

Meteorites

In the Allende meteorite , wadalite was found in calcium-aluminum-rich inclusions (CAI) together with wollastonite, grossular and monticellite between anorthite and Åkermanite . It is believed that wadalite was formed when Åkermanite and anorthite or grossular were transformed by a chlorine-containing fluid .

Pyrometamorphic clinker from coal heaps

Wadalite was found together with kumtyubeit , oldhamite and jasmundite in a lime silicate clinker tuber from the burned overburden dump of the Kalinin coal mine in the Donets Basin , Ukraine .

In the spent spoil heap of the Baturinskaya-Vostochnaya-1-2 mine, chloromayenite-wadalite mixed crystals in granular aggregates of fluorellestadite and cuspidin were detected.

A similar occurrence is the burnt waste dump of the coal mines in the Rosice - Oslavany coal field, Okres Brno-venkov in the Czech Republic .


Web links

Commons : Wadalite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f g h 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]).
  2. ↑ a b c d e f g h i j K. Tsukimura, Y. Kanazawa, M. Aoki and M. Bunno: Structure of wadalite Ca 6 Al 5 Si 2 O 16 Cl 3 . In: Acta Crystallographica Section C . C49, 1993, pp. 205-207 , doi : 10.1107 / S0108270192005481 .
  3. ↑ a b c d e f g Yasuo Kanazawa, Masahiro Aoki, Hideo Takeda: Wadalite, rustumite, and spurrite from La Negra mine, Queretaro, Mexico . In: Bulletin of the Geological Survey of Japan . tape 48 , 1997, pp. 413-420 ( gsj.jp [PDF; 2.8 MB ; accessed on June 30, 2018]).
  4. ↑ a b FP Glasser: Comments on wadalite, Ca 6 Al 5 SiO 16 Cl 3 , and the structures of garnet, mayenite and calcium chlorosilicate. Addendum . In: Acta Crystallographica Section C . tape 51 , 1995, p. 340 ( wiley.com [PDF; 105 kB ; accessed on June 30, 2018]).
  5. ↑ a b c d e f g h i j k Tamara Mihajlovic, Christian L. Lengauer, Theodoros Ntaflos, Uwe Kolitsch and Ekkehart Tillmanns: Two new minerals, rondorfite, Ca 8 Mg [SiO 4 ] 4 Cl 2 , and almarudite, K ( □, Na) 2 (Mn, Fe, Mg) 2 (Be, Al) 3 [Si 12 O 30 ], and a study of iron-rich wadalite, Ca 12 [(Al 8 Si 4 Fe 2 ) O 32 ] Cl 6 , from the Bellerberg (Bellberg) volcano, Eifel, Germany . In: New Yearbook for Minaralogy Treatises . tape 179 , 2004, pp. 265–294 ( researchgate.net [PDF; 4.7 MB ; accessed on June 30, 2018]).
  6. ↑ a b c d e f g h i j k l Yasuyuki Banno, Michiaki Bunno and Katsuhiro Tsukimura: A reinvestigation of holotype wadalite from Tadano, Fukushima Prefecture, Japan . In: Mineralogical Magazine - preprint . 2017 ( cambridge.org [PDF; 913 kB ; accessed on September 8, 2018]).
  7. ↑ 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 .
  8. ↑ 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]).
  9. ^ A b Qiu Ling Feng, Frederic P. Glasser, R. Allen-Howie, Eric E. Lachowski: Chlorosilicate with the 12Ca O.7 Al 2 O 3 structure and its relationship to garnet . In: Acta Crystallographica Section C . C44, 1988, pp. 589-592 , doi : 10.1107 / S0108270187012046 .
  10. ↑ Mindat - Wadalit
  11. ↑ R. Bailau, EV Galuskin, VM Gazeev, NN Pertzev: Classification and potential new minerals in the "mayenite" group . In: Acta Mineralogica Petrographica Abstract Series. 20th General Meeting of the International Mineralogical Association August 21-27, 2010. Budapest, Hungary . tape 6 , 2010, p. 493–493 ( rruff.info [PDF; 645 kB ; accessed on June 30, 2018]).
  12. ↑ Evgeny V. Galuskin, Irina O. Galuskina, Radu Bailau, Krystian Prusik, Viktor M. Gazeev, Aleksandr E. Zadov, Nikolai N. Pertsev, Lidia Jeżak, Anatoly G. Gurbanov, Leonid Dubrovinsky: Eltyubyuite, Ca 12 Fe 3+ 10 Si 4 O 32 Cl 6 - the Fe3 + analogue of wadalite: a new mineral from the Northern Caucasus, Kabardino-Balkaria, Russia . In: European Journal of Mineralogy . tape 25 , 2013, p. 221-229 , doi : 10.1127 / 0935-1221 / 2013 / 0025-2285 .
  13. ↑ Chi Ma, Alexander N. Krot: Discovery of a new Cl-rich silicate mineral, Ca 12 (Al 2 Mg 3 Si 7 ) O 32 Cl 6 : An alteration phase in Allende . In: Meteoritics and Planetary Science . 49 (S1), 2014, pp. 1 ( caltech.edu [PDF; 256 kB ; accessed on June 30, 2018]).
  14. ↑ Chi Ma and Alexander N. Krot: Adrianite, Ca 12 (Al 4 Mg 3 Si 7 ) O 32 Cl 6 , a new Cl-rich silicate mineral from the Allende meteorite: An alteration phase in a Ca-Al-rich inclusion . In: American Mineralogist . In Press, 2018 ( minsocam.org [PDF; 1.5 MB ; accessed on July 22, 2018]).
  15. ↑ a b Mindat - Number of localities for wadalite
  16. ↑ Hope A. Ishii, Alexander N. Krot, John P. Bradley, Klaus Keil, Kazuhide Nagashima, Nick Teslich, Benjamin Jacobsen, and Qing-Zhu Yin: Discovery, Mineral Paragenesis and Origin of Wadalite in Meteorites . In: American Mineralogist . tape 95 , 2010, p. 440–448 ( llnl.gov [PDF; 1.4 MB ; accessed on June 30, 2018]). Discovery, Mineral Paragenesis and Origin of Wadalite in Meteorites ( Memento from February 12, 2017 in the Internet Archive )
  17. ↑ Victor Victorovich Sharygin: Mineralogy of Ca-rich Metacarbonate Rocks from Burned Dumps of the Donetsk Coal Basin . 2010, p. 162–170 ( researchgate.net [PDF; 563 kB ; accessed on June 30, 2018]).
  18. ↑ Victor Victorovich Sharygin: Mayenite-supergroup minerals from burned dump of the Chelyabinsk Coal Basin . In: Russian Geology and Geophysics . tape 56 , 2015, p. 1603–1621 ( researchgate.net [PDF; 7.1 MB ; accessed on June 30, 2018]).