Katoite

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Katoite
Katoite-432741.jpg
Clear, spherical katoite crystals on magnetite from the Caspar quarry, Ettringer Bellerberg , Mayen, Eifel, Rhineland-Palatinate (field of view 3 mm)
General and classification
other names

IMA 1982-080

chemical formula Ca 3 Al 2 3+ (OH) 12
Mineral class
(and possibly department) 		Oxides and hydroxides
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Ia 3 d (No. 230)Template: room group / 230
Lattice parameters a  = 12.358 (natural), 12.5731 (synthetic, Si-free)  Å
Formula units Z  = 8
Frequent crystal faces Octahedron {111}, icositetrahedron {112}
Physical Properties
Mohs hardness 5 to 6; 6 to 7
Density (g / cm 3 ) calculated: 2.76 (natural)
Cleavage Please complete!
colour fallowless
Line color White
transparency transparent
shine Glass gloss
Crystal optics
Refractive index n  = 1.632

The mineral katoite is a very rare hydroxide from the upper group of the garnet with the simplified composition Ca 3 Al 2 (OH) 12 . It crystallizes in the cubic crystal system with the structure of garnet. Katoite usually forms colorless, milky, cloudy crusts, more rarely columnar aggregates of octahedral crystals. The crystals, which are seldom visible to the naked eye, are colorless and transparent with a size of less than one millimeter.

Katoite is found in the cavities of volcanic rocks or at the contact of limestone xenolites with the surrounding volcanic rock. Apart from its type locality , the phonolite quarry near Montalto di Castro , Latium in Italy , Katoite has so far only been found in a few other places in the world.

Outside of nature, katoite forms when aluminum-containing cements set, such as Portland cement , and is therefore part of one of the most important building materials of the industrial age. In the geosciences, katoite is the model substance for incorporating water into nominally anhydrous silicates by replacing SiO 4 with (OH) 4 . In addition to most grenades, (OH) 4 defects have been detected in olivine and coesite, for example, and play an important role in understanding the processes in the earth's mantle.

Etymology and history

Water-containing garnets with less than 6 H 2 O or more than 1.5 SiO 2 per formula unit have been known since the beginning of the 20th century. F. Cornu described Hibschite in 1906 , unfortunately with the wrong composition CaO • Al 2 O 3  • 2SiO 2  • 2H 2 O. In 1920 William F. Foshag described the mineral plazolite with the composition 3CaO • Al 2 O 3  • 2 (SiO 2 , CO 2 ) • 2H 2 O, which at that time he ascribed to the sodalite group . Adolf Pabst was able to assign plazolite to the garnet group in his structural investigation in 1937 and Beliankin & Petrov showed in 1941 that hibschite and plazolite are largely identical in composition and properties. They described hibschite / plazolite as a grossular in which a SiO 2 was replaced by 2H 2 O and introduced the term grossularoid for these minerals. In 1943, CO Hutton et al. the name hydrogrossular for grenades with compositions between grossular and hibschit. All grossular katoite mixed crystals with an unknown OH content are currently referred to as hydrogrossular. Since the reorganization of the garnet group by the IMA in 2013, hibschit is no longer considered a mineral and all hydrogrossulars with more than 1.5 Si per formula unit are called grossulars.

Long before katoite, a hydrogrossular with less than 1.5 SiO 2 per formula unit, was found in nature in 1984, synthetic phases were characterized with such compositions. As early as 1941 Flint and coworkers published their investigations on synthetic phases with compositions between grossular and the SiO 2 -free end member 3CaO • Al 2 O 3  • 6H 2 O. They proved the existence of a complete isomorphic mixture series between these end members, certain lattice constants and refractive indices and coined the term hydro grenade for this mixture series, which also included Plazolith. 23 years later, Claudine Choen-Addad and her colleagues determined the position of the protons in the garnet structure of the synthetic hydrogarnet end link and thus substantiated the previously published hypothesis of the isomorphic exchange of SiO 2 for 4 (OH) groups.

The mineral katoite was not described until 20 years later, in 1984, by Elio Passasslia and Romano Rinaldi and named after Akira Kato from the National Museum of Natural Sciences in Tokyo . Kato was the chairman of the IMA Commission on New Minerals, Mineral Names and Classifications (CNMNC) and Katoite was the last mineral to be recognized by the CNMNC under his chairmanship.

classification

The current classification of the International Mineralogical Association (IMA) counts the katoite to the garnet upper group, where so far (2013) it is the only mineral with a completely unoccupied tetrahedrally coordinated lattice position.

In the outdated, but still in use 8th edition of the mineral classification according to Strunz , the katoite belonged to the mineral class of "silicates and germanates", where it was classified in the department of island silicates with almandine , andradite , calderite , goldmanite , grossular , henritermierite , hibschite , holtstamite , Hydrougrandit , Kimzeyit , Knorringit , majorite , Morimotoit , Pyrop , Schorlomit , Spessartin , Uwarowit , wadalite and Yamatoit (discredited because identical to Momoiit ) the "garnet group" with the system number. VIII / A.08 forms.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001, also assigns katoite to the class of "silicates and germanates". There, according to its composition and structure, it is classified in department A (island silicates (nesosilicates)) in sub-department D. Island silicates without further anions; Cations in octahedral [6] and usually larger coordination with the minerals almandine, andradite, blythite (H), calderite, goldmanite, grossular, henritermierite, hibschite (Rn), holtstamite, hydroandradite (N), kimzeyite, knorringite , majorite , momoiite ( IMA 2009-026), Morimotoit, Pyrope, Schorlomit, Skiagit (H), Spessartin, Uwarowit and Wadalit also belong to the "Garnet Group" with the system no. 9.AD.25 counted.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the katoite to the class of "silicates and germanates" and there in the department of "island silicates: SiO4 groups only with cations in [6] and> [6] coordination." ", Where with the meanwhile discredited mineral hibschit the" garnet group (hydrogranate) "with the system no. 51.04.03d forms.

Crystal structure

Katoite crystallizes with cubic symmetry in space group Ia 3 d (space group no. 230) with 8 formula units per unit cell . The lattice parameter varies depending on the silicon content between a  = 12.5731  Å (Si-free) and 12.25 Å (1.5 Si). Template: room group / 230

The structure is that of garnet . Calcium (Ca 2+ ) occupies the dodecahedral X position surrounded by 8 oxygen ions, aluminum (Al 3+ ) the octahedral Y position surrounded by 6 oxygen ions and the tetrahedral Z position surrounded by 4 oxygen ions is predominantly unoccupied. The hydrogen ions of the OH groups lie above the tetrahedral surfaces of the unoccupied Z position. The information on the exact position is different. The first structural determinations see the protons just inside the empty tetrahedron position, whereas all more recent works show proton positions outside the tetrahedron.

Investigations of the grossular katoite mixed crystal series revealed no evidence of an orderly incorporation of the OH groups and the associated lowering of symmetry or the formation of OH- and Si-rich domains in the mixed crystal over the entire composition range. This indicates that the lowering of the symmetry of the Holtstamite is primarily caused by the incorporation of the Jahn-Teller ion Mn 3+ .

Katoite undergoes a phase transition at high pressure of around 5 GPa. Katoit with space group Ia 3 d (space group no.230) changes to a high pressure phase with space group I 4 3 d (space group no.220) . Template: room group / 230 Template: room group / 220

Chemism

Katoite is the (OH) 4 analog of Grossular, with which it forms a mixed crystal row according to the exchange reaction

  • [Z] □ + (OH) - 4 = [Z] Si 4+ + O 2- 4

In this series, all compositions with less than 50% gross component, i.e. less than 1.5 Si per formula unit, are referred to as katoite. The measured composition from the type locality is [X] Ca 2.96 [Y] (Al 1.85 Mg 2+ 0.01 □ 0.14 ) [Z] (Si 0.69 S 0.11 □ 2.2 ) O 2.93 (OH) 9.07 . Small amounts of Si 4+ can be replaced by S 6+ . The slight understaffing of the Y position indicates a charge equalization through vacancies in this position:

  • 2 [Y] Al 3+ + 3 [Z] Si 4+ = 2 [Y] □ + 3 [Z] S 6+

In the type locality of Hibschit, hydrogrossular occurs together with gypsum . Also this grossular, [X] Ca 3 [Y] (Al 1.61 Fe 3+ 0.22 Mg 2+ 0.10 □ 0.07 ) [Z] (Si 1.50 S 0.17 □ 1.33 ) O 6.64 (OH) 5.36 , has comparable amounts of sulfur on the silicon position. In addition, it contains some andradite / hydroandradite according to the exchange reaction:

  • [Y] Al 3+ = [Y] Fe 3+

Synthetic hydrogrosulars made from hydrated cements also show this pattern of compositions: 1.3 - 2.1 vacancies and low levels of sulfur (0.05 - 0.1 apfu) on the silicon position [Z], and Fe 3+ (0.04 - 0.22 apfu), Mg 2+ (0.03-0.07 apfu) and vacancies (0-0.5) on the octahedral [Y] position. Two exchange reactions are proposed for the replacement of Al by Mg:

  • [Y] Al 3+ + O = [Y] Mg 2+ + OH
  • 2 [Y] Al 3+ + [Z] Si 4+ = 2 [Y] Mg 2+ + [Z] S 6+

Grossular katoite mixed crystals were synthesized over the entire composition range. There were no signs of gaps in the mixed crystal row. On the other hand, the so-called "pink jade" from the Bushveld complex in South Africa consists of a dense intergrowth of two different hydrogrossulars with 2.65 and 2.5 Si per formula unit, which could indicate a narrow miscibility gap. Further indications of a miscibility gap can be found in studies of the hydration behavior of cement . Here pure katoite forms at 20 ° C, and two different hydrogrossulars with 0.42 and 0.76 Si at 110 ° C, which indicates a miscibility gap between these compositions. Other authors report a miscibility gap between 0.42 and 1.50 Si per formula unit at 95 ° C, between 1.0 and 1.6 Si at 200 ° C and between 1.8 and 2.2 Si above 250 ° C per formula unit.

Education and Locations

The Si content of hydrogrossulars increases with increasing temperatures. Katoite consequently forms near the surface in cavities of low-silicon volcanic rocks at low temperatures of up to ~ 300 ° C. At its type locality, the phonolite quarry near Montalto di Castro , Latium in Italy , it forms thin microcrystalline crusts or columnar aggregates in cavities in the phonolite. The octahedral crystals are 0.1-0.3 mm in size and rounded. Katoite occurs here in paragenesis with tobermorite , afwillite and hydrocalumite . Other minerals in this locality are opal , portlandite , quartz , hematite , gypsum , calcite , apophyllite , cordierite , jennite , strätlingite and the zeolites chabazite , gismondine and phillipsite .

Another location is the Dazit quarry on Csódi Hill in Dunabogdány , Szentendre in Pest County , Hungary . Katoite occurs here as a colorless crust of octahedral crystals (0.1 mm) at the contact of calcium silicate xenolites with the dacite. Accompanying minerals are brucite , lizardite , chrysotile , deweylite , smectite and calcite in the xenolites and plagioclase , biotite , amphibole , glass and garnet in the dacite.

In the Eifel , katoite was found in xenolites in alkali basalts. Accompanying minerals here are fluorellestadite , wadalite , andradite - schorlomite , perovskite , gehlenite , magnesioferrite , cuspidine , ettringite - thaumasite , hydrocalumite , jennite , portlandite and wernerkrauseit .

Other sites (as of 2017) are the basalt quarry on Zeilberg near Maroldsweisach in Bavaria , Germany, the basalt quarry on Láz Hill, Uzsabánya in Veszprém County , Hungary, some outcrops of the Hatrurim Formation in Negev , Israel and Flekkeren near Skien in Telemark , Norway .

See also

Web links

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

Individual evidence

  1. ^ IMA / CNMNC List of Mineral Names; May 2017 ( Memento from July 21, 2017 in the Internet Archive )
  2. ↑ a b c d e f g h i j k l m n o p q r Elio Passasslia and Romano Rinaldi: Katoite, a new member of the Ca 3 Al 2 (Si0 4 ) 3 -Ca 3 Al 2 (OH) 12 series and a new nomenclature for the hydrogrossular group of miners. In: Bull. Mineral. tape 107 , 1984, pp. 605-618 ( researchgate.net [PDF; 11.3 MB ; accessed on June 4, 2017]).
  3. ↑ a b c Konstantinos Kyritsis, Nicola Meller and Christopher Hall: Chemistry and Morphology of Hydrogarnets Formed in Cement-Based CASH Hydro Ceramics Cured at 200 ° to 350 ° C . In: J. Am. Ceram. Soc. tape 92 , 2009, p. 1105–1111 ( amazonaws.com [PDF; 956 kB ; accessed on July 2, 2017]).
  4. ↑ Mindat - Katoite (English)
  5. ↑ Webmineral - Katoite (English)
  6. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  7. ↑ a b c Oratio Ferro, Ermanno Galli, Gabor Papp, Simona Quartieri, Sandor Szakall and Giovanna Vezzalini: A new occurrence of katoite and re-examination of the hydrogrossular group . In: European Journal of Mineralogy . tape 15 , 2003, p. 419-426 ( researchgate.net [PDF; 297 kB ; accessed on June 4, 2017]).
  8. ↑ a b List of localities for katoite in the Mineralienatlas and Mindat
  9. ↑ George R. Rossman, Roger D. Aines: The hydrous components in garnets: Grossular-hydrogrossular . In: The American Mineralogist . tape 76 , 1991, pp. 1153–1164 ( minsocam.org [PDF; accessed June 4, 2017]).
  10. ↑ Sylvia-Monique Thomas, Monika Koch-Müller, Patrick Reichart, Dieter Rhede, Rainer Thomas, Richard Wirth, Stanislav Matsyuk: IR calibrations for water determination in olivine, r-GeO2, and SiO2 polymorphs . In: Phys Chem Minerals . tape 36 , 2009, p. 489-509 , doi : 10.1007 / s00269-009-0295-1 ( researchgate.net [PDF; 912 kB ; accessed on June 29, 2017]).
  11. ↑ Koch-Müller, M., Dera, P., Fei, Y., et al .: OH– in synthetic and natural coesite. In: The American Mineralogist . tape 88 , 2015, p. 1436-1445 , doi : 10.2138 / am-2003-1007 .
  12. ^ Edward S. Grew, Andrew J. Locock, Stuart J. Mills, Irina O. Galuskina, Evgeny V. Galuskin and Ulf Hålenius: IMA Report - Nomenclature of the garnet supergroup . In: American Mineralogist . tape 98 , 2013, p. 785–811 ( rruff.info [PDF; 1.1 MB ; accessed on April 28, 2020]).
  13. ^ A b Claudine Cohen-Addad, P. Ducros, A. Durif, EF Bertaut, A. Delapalme: Détermination de la position des atomes d'hydrogène dans l'hydrogrenat Al 2 O 3 , 3CaO, 6H 2 O par résonance magnétique nucléaire et diffraction neutronique. In: Journal de Physique . tape 25 , 1964, pp. 478–483 ( archives-ouvertes.fr [PDF; 1,3 MB ; accessed on June 4, 2017]).
  14. ↑ M. Sacerdoti, E. Passaglia: The crystal structure of katoite and implications within the hydrogrossular group of minerals . In: Bulletin de Mineralogie . tape 108 , 1985, pp. 1-8 .
  15. ↑ a b c C. Cohen-Addad, P. Ducros, EF Bertaut: Etude de la substitution du groupement SiO4 par (OH) 4 dans les composes Al2Ca3 (OH) 12 et Al2Ca3 (SiO4) 2.16 (OH) 3.36 de type grenat . In: Acta Crystallographica . tape 23 , 1967, p. 220–230 , doi : 10.1107 / S0365110X67002518 ( iucr.org [accessed June 4, 2017]).
  16. ↑ George A. Lager, Thomas Armbruster, J. Faber: Neutron and X-ray diffraction study of hydrogarnet Ca3Al2 (O4H4) . In: The American Mineralogist . tape 72 , 1987, pp. 756–765 ( minsocam.org [PDF; 1.1 MB ; accessed on June 4, 2017]).
  17. ↑ George A. Lager, Thomas Armbruster, Frank J. Rotella, George R. Rossman: OH substitution in garnets: X-ray and neutron diffraction, infrared, and geometric-modeling studies . In: The American Mineralogist . tape 74 , 1989, pp. 840–851 ( minsocam.org [PDF; 1.5 MB ; accessed on June 4, 2017]).
  18. ↑ a b George A. Lager, Robert T. Downs, Marcus Origlieri, and Rebecca Garoute: High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition from Ia3d to I-43d symmetry at 5 GP . In: The American Mineralogist . tape 87 , 2002, pp. 642–647 ( rruff.info [PDF; 141 kB ; accessed on June 4, 2017]).
  19. ^ A b George A. Lager, William G. Marshall, Zhenxian Liu and Robert T. Downs: Re-examination of the hydrogarnet structure at high pressure using neutron powder diffraction and infrared spectroscopy . In: The American Mineralogist . tape 90 , 2005, pp. 639–644 ( rruff.info [PDF; 286 kB ; accessed on June 4, 2017]).
  20. ^ Romano Rinaldi and Elio Passasslia: Hibschite topotype: crystal chemical characterization . In: European Journal of Mineralogy . tape 1 , 1989, pp. 639-644 ( researchgate.net [PDF; 4.2 MB ; accessed on July 1, 2017]).
  21. ↑ Weiji Cheng, Hugh J. Greenwood, Hongliang Hu and David C. Frost: XRD and XPS Analyzes of the Grossular-Hydrogrossular Series . In: The Canadian Mineralogist . tape 28 , 1990, pp. 87–91 ( rruff.info [PDF; accessed June 4, 2017]).
  22. ^ PG Manning, DR Owens: Electron Microprobe, X-Ray Diffraction, and Spectral Studies of South African and British Columbian "Jades" . In: The Canadian Mineralogist . tape 15 , 1977, pp. 512-517 ( rruff.info [PDF; accessed June 4, 2017]).
  23. ↑ Belay Zeleke Dilnesa, Barbara Lothenbach, Guillaume Renaudin, Adrian Wichser, Dmitrii Kulik: Synthesis and characterization of hydrogarnet Ca3 (AlxFe1 - x) 2 (SiO4) y (OH) 4 (3 - y) . In: Cement and Concrete Research . tape 59 , 2014, p. 96 - 111 ( free.fr [PDF; 2.6 MB ; accessed on June 4, 2017]).
  24. ↑ TG Jappy and FP Glasser: Synthesis and stability of silica-substituted hydrogarnet Ca3Al2 Si3-xO12-4x (OH) 4x . In: Advances in Cement Research . tape 4 , 1991, pp. 1 - 8 , doi : 10.1680 / adcr.1991.4.1.1 .
  25. ↑ Nicola Meller, Konstantinos Kyritsis, Christopher Hall: The mineralogy of the CaO-Al2O3-SiO2-H2O (CASH) hydro-ceramic system from 200 to 350 ° C . In: Cement and Concrete Research . 2008, doi : 10.1016 / j.cemconres.2008.10.002 ( amazonaws.com [PDF; 1.1 MB ; accessed on June 4, 2017]).
  26. ↑ Hatten S. Yoder Jr .: Stability Relations of Grossularite . In: The Journal of Geology . tape 58 , 1950, pp. 221-253 , doi : 10.1086 / 625736 .
  27. ↑ Evgeny V. Galuskin, Biljana Kruger, Hannes Krüger, Günter Blass, Remo Widmer, Irina O. Galuskina: Wernerkrauseite, CaFe3 + 2Mn4 + O6: the first nonstoichiometric post-spinel mineral, from Bellerberg volcano, Eifel, Germany . In: European Journal of Mineralogy . tape 28 , 2016, p. 485–495 , doi : 10.1127 / ejm / 2016 / 0028-2509 .