Grossular

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Grossular
Grossular-137781.jpg
"Gooseberry-colored" grossular from Sibinndi, Nioro du Sahel , Kayes region, Mali (size: 4.9 × 3.4 × 2.9 cm)
General and classification
chemical formula Ca 3 Al 2 [SiO 4 ] 3
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.AD.25 ( 8th edition : VIII / A.08)
51.04.03b.02
Similar minerals Uvarovite , leucite , emerald , tourmaline
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  = 11.851  Å
Formula units Z  = 8
Physical Properties
Mohs hardness 6.5 to 7
Density (g / cm 3 ) measured: 3.594; calculated: 3.5952
Cleavage rarely secretions after {110}
Break ; Tenacity uneven to scalloped, brittle
colour colorless, yellow green to dark green, golden yellow, pink, red, orange, yellowish brown to reddish brown
Line color White
transparency transparent to opaque
shine Glass gloss to resin gloss
Crystal optics
Refractive index n  = 1.734
Birefringence none, often abnormally birefringent

Grossular is a common mineral from the garnet group within the mineral class of " silicates and germanates ". It crystallizes in the cubic crystal system with the idealized composition Ca 3 Al 2 [SiO 4 ] 3 , so it is chemically a calcium - aluminum - island silicate .

Grossular usually develops dodecahedral or trapezoidal crystals , but also granular to massive mineral aggregates . In its pure form, the mineral is colorless and transparent. However, since it forms a complete mixed crystal row with andradite and uvarowite on the one hand and can contain various foreign admixtures on the other hand, it usually occurs in different colors, although a yellow-green to dark green color predominates, which also gave the grossular its name. There are also golden yellow, pink to red, orange and yellowish brown to reddish brown grossulare, some of which have received different proper names.

Etymology and history

Grossular was named in 1811 by Abraham Gottlob Werner , who named the mineral after the Latin word for gooseberry ( ribes grossularia ) because of its often green color .

As type locality is considered Chernyshevsk (Chernyshevsk) in Vilyuy River basin in the Far Eastern Republic of Sakha (Yakutia).

classification

The structural classification of the International Mineralogical Association (IMA) is one of the Grossular to Garnet supergroup, where he along with almandine , Andradite , Calderit , Eringait , Goldmanit , Knorringit , Morimotoit , majorite , Menzerit- (Y) , Momoiit , pyrope , Rubinit , Spessartine and Uvarowite form the garnet group with 12 positive charges on the tetrahedrally coordinated lattice position.

Already in the 8th edition of the mineral systematics according to Strunz , which is now outdated, but still in use , the grossular belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates (nesosilicates)", where together with andradite , goldmanite and uwarowite the independent "Garnet Group - Ugrandit Series" with the system no. 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 assigns the grossular to the class of "silicates and germanates" and there in the department of "island silicates (nesosilicates)". This section is further subdivided according to the possible presence of further anions as well as the coordination of the cations involved , so that the mineral can be classified according to its composition and structure in the subdivision of “island silicates without further anions; Cations "is to find where it along with almandine, Andradite, Calderit, Goldmanit in oktahedraler [6] and usually greater coordination Henritermierit , Holtstamit , katoite , Kimzeyit , Knorringit, majorite, Morimotoit, pyrope, Schorlomit , Spessartin and Uwarowit the" Garnet group "with the system no. 9.AD.25 forms. The garnet compounds blythite, hibschite, hydroandradite and skiagite, which are no longer regarded as minerals, were also included in this group. Wadalite , at that time still grouped with the grenades, proved to be structurally different and is now assigned to a separate group with chloromayenite and fluoromayenite . The garnets irinarassite , hutcheonite , kerimasite , toturite , menzerite (Y) and eringaite described after 2001 would have been classified in the garnet group.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the grossular to the class of "silicates and Germanates" and there in the department of "island silicate minerals ". Here it is together with andradite, goldmanite, uwarovite and yamatoite (discredited because it is identical to momoiite ) in the "garnet group (Ugrandite series)" with the system no. 51.04.03b to be found in the subsection “ Island silicates: SiO4 groups only with cations in [6] and> [6] coordination ”.

Chemism

Grossular with the idealized composition [X] Ca 2+ 3 [Y] Al 3+ [Z] Si 3 O 12 is the calcium -Analog of Pyrop ( [X] Mg 2+ 3 [Y] Al [Z] Si 3 O 12 ) as well as the aluminum analog of Andradit and Uwarowit. The position in the garnet structure is indicated in the square brackets.

Grossular forms mixed crystals with most other silicate grenades. At the octahedrally coordinated Y position, aluminum Al 3+ can be replaced by various cations, depending on the exchange reactions

  • [Y] Al 3+ = [Y] Fe 3+ , (andradite),
  • [Y] Al 3+ = [Y] Cr 3+ , (uwarowite),
  • [Y] Al 3+ = [Y] V 3+ , (goldmanite),
  • [Y] Al 3+ = [Y] Sc 3+ , (Eringaite)

On the dodecahedrally coordinated X position, calcium Ca 2+ can be replaced by magnesium Mg 2+ , manganese Mn 2+ and iron Fe 2+ , according to the exchange reactions

  • [X] Ca 2+ = [X] Mg 2+ (pyrope),
  • [X] Ca 2+ = [X] Mn 2+ (Spessartine),
  • [X] Ca 2+ = [X] Fe 2+ (almandine)

Only in the mixture of grossular-pyrope there is a miscibility gap at temperatures below 600 ° C and 25–30 mol% grossular.

Grossular forms a seamless mixed realm with the hydroxide katoite . Silicon is replaced by four protons (H + ) and a space (□), according to the substitution

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

Mixed crystals with more than 50 mol% grossular content are referred to as grossular. The term hydrogrossular is also used for mixed crystals with an unspecified composition. Hibschite (plazolite) ( [X] Ca 2+ 3 [Y] Al 3+ [Z] (Si 1.5 □ 1.5 ) O 6 6 12 ) is a variety of Grossular and not an independent mineral.

Crystal structure

Grossular crystallizes with cubic symmetry in space group Ia 3 d (space group no. 230) with 8 formula units per unit cell . There are numerous provisions for the edge length of the cubic unit cell of both natural mixed crystals and synthetic grossulars. For the pure grossular terminal the lattice parameter is z. B. with a  = 11.851 Å Template: room group / 230

The structure is that of garnet . Calcium (Ca 2+ ) occupies the dodecahedral X positions 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 exclusively silicon (Si 4+ ) occupied.

Natural grossulars often show sector zoning and are optically slightly birefringent , which is usually interpreted as an indication of a lower, non-cubic symmetry. For birefringent grossulare from the asbestos mines Eden Mills in Vermont , USA and Lake Asbestos in Quebec , Canada , z. B. triclinic symmetry determined, caused among other things by an ordered distribution of Al 3+ and Fe 3+ on the 8 different octahedrally coordinated positions of the triclinic garnet structure as well as Fe 2+ and Ca 2+ on the different dodecahedrally coordinated X positions.

In new studies with high-resolution synchrotron - X-ray diffraction , however, could be shown that birefringent Grossularite are a mixture of two shells of different composition. Both grenades are cubic with slightly different lattice constants . It is these different grenade lattice constants that lead to lattice stresses and consequently stress birefringence .

Modifications and varieties

Tsavorite with graphite from the Merelani Hills (Mererani), Lelatema Mountains, Arusha , Tanzania (size: 2.3 × 1.7 × 1.6 cm)

Several varieties of grossular are known:

  • Hessonite : due to the addition of Fe 3+ ions, orange-red to hyacinth-red colored grossular. An outdated and no longer in use name for the hessonite was cinnamon stone or Kaneel stone (after Abraham Gottlob Werner ). René-Just Haüy named the variety after the Greek word hesson for lower , based on its lower value compared to the "real" hyacinth ( zircon variety ).
  • Leukogranat (from ancient Greek λευκός leukós "white") is the colorless variant of the grossular.
  • the emerald green tsavorite or tsavolite was only discovered in 1974.

Education and Locations

"Raspberry-colored" grossular with yellowish-brown Vesuvianite from Lake Jaco , Sierra de la Cruz , Sierra Mojada , Coahuila , Mexico (size: 5.0 × 4.4 × 1.8 cm)

Grossular often forms in contact and regionally metamorphic , calcium-rich rocks such as skarn or rodingite , but can also arise through hydrothermal processes on fissures of these rocks as well as in marl-like calcareous silicate rock and occasionally in schists and serpentinites .

Accompanying minerals include calcite , clinozoisite , diopside , dolomite , epidote , quartz , scapolite , tremolite , vesuvianite and wollastonite . Especially with Vesuvianite, to which the grossular looks very similar, it can easily be confused due to the narrow paragenesis.

Grossular has already been proven to be a relatively frequent mineral formation at many sites, of which around 1,600 sites are known to date (as of 2015).

In Germany, the mineral has so far been found at several sites in the Black Forest in Baden-Württemberg, at many sites in Bavaria (Franconia, Upper and Lower Bavaria), near Hirzenhain and several sites in the Odenwald in Hesse, near Bad Harzburg and Sankt Andreasberg in Lower Saxony several places in the Eifel such as at Niedermendig and Ettringer Bellerberg , at Rammelsbach and Wolfstein in Rhineland-Palatinate, in the Ore Mountains and in the Vogtland in Saxony, at several places in Schleswig-Holstein and at Unterbreizbach in Thuringia.

In Austria, Grossular was found mainly in Carinthia , Salzburg and Styria . He was also able to go to the Kanitzriegel near Bernstein in Burgenland; near Schwallenbach , on Arzberg and the Siebenhandl quarry near Felbring (Maria Laach am Jauerling) in Lower Austria; at several locations in the Hinterbichler Dorfertal and in the Zillertal in Tyrol; in the Upper Austrian municipality of Aigen in the Mühlkreis and on the Putzkammer Alp in the Verwall group in Vorarlberg.

In Switzerland, the mineral was found in the district of Bergell and Vorderrheintal in Graubünden , in the Mattertal and Saas Valley in Valais and near Santa Maria di Claro ( Claro TI ) in the canton of Ticino .

Other sites are in Afghanistan, Egypt, the Antarctic, Argentina, Australia, Brazil, Bulgaria, China, Ecuador, Finland, France, Greece, Greenland, Guinea, Honduras, India, Iraq, Iran, Ireland, Israel, Italy, Jamaica , Japan, Cambodia, Canada, Kenya, Colombia, Korea, Madagascar, Mali, Morocco, Mexico, Mongolia, Namibia, New Zealand, Norway, Pakistan, Peru, Poland, Portugal, Romania, Russia, Saudi Arabia, Slovakia, Spain , Sri Lanka, Sweden, South Africa, Taiwan, Tanzania, the Czech Republic, Turkey, Ukraine, Hungary, the US Virgin Islands, the United Kingdom (Great Britain) and the United States of America (USA).

use

Faceted hessonite, 1ct, Sri Lanka

Like many other garnets, grossulare are valued and valuable gemstones which, depending on the quality, are either made into different facet cuts or into cabochons .

Web links

Commons : Grossular  - collection of images, videos and audio files
Wiktionary: Grossular  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ A b Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  541 (English).
  2. ^ David Barthelmy: Grossular Mineral Data. In: webmineral.com. Retrieved September 8, 2019 .
  3. ↑ a b c Georg Menzer: The crystal structure of the grenade . In: Journal of Crystallography - Crystalline Materials . tape 69 , 1929, pp. 300-396 , doi : 10.1524 / zkri.1929.69.1.300 .
  4. ^ A b GA Novak, GV Gibbs: The crystal chemistry of the silicate garnets . In: The American Mineralogist . tape 56 , 1971, p. 791–825 (English, rruff.info [PDF; 2,3 MB ; accessed on September 8, 2019]).
  5. ↑ a b c d BJ Skinner: Physical properties of end members of the garnet group . In: The American Mineralogist . tape 41 , 1956, pp. 428–436 (English, minsocam.org [PDF; 522 kB ; accessed on May 5, 2018]).
  6. ↑ a b c d DK Teertstra: Index-of-refraction and unit-cell constraints on cation valence and pattern of order in garnet-group minerals . In: The Canadian Mineralogist . tape 44 , 2006, pp. 341–346 (English, rruff.info [PDF; 197 kB ; accessed on September 8, 2019]).
  7. ↑ a b c Jibamitra Ganguly, Weiji Cheng, Hugh St. C. O'Neill: Syntheses, volume, and structural changes of garnets in the pyrope-grossular join: Implications for stability and mixing properties . In: American Mineralogist . tape 78 , 1993, p. 583–593 (English, rruff.info [PDF; 1,3 MB ; accessed on September 8, 2019]).
  8. ↑ a b c Grossular . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 73  kB ; accessed on September 8, 2019]).
  9. ↑ a b Fred M. Allen, Peter R. Buseck: XRD, FTIR, and TEM studies of optically anisotropic grossular garnets . In: The American Mineralogist . tape 73 , 1988, pp. 568–584 (English, rruff.info [PDF; 1.7 MB ; accessed on September 8, 2019]).
  10. ^ A b Anne M. Hofmeister, Rand B. Schaal, Karla R. Campbell, Sandra L. Berry and Timothy J. Fagan: Prevalence and origin of birefringence in 48 garnets from the pyrope-almandine-grossularite-spessartine quaternary . In: The American Mineralogist . tape 83 , 1998, pp. 1293–1301 (English, minsocam.org [PDF; 106 kB ; accessed on September 8, 2019]).
  11. ^ CAS Hoffmann: Handbook of Mineralogy . tape 1 . Craz and Gerlach, Freiberg 1811, p. 479–481 ( rruff.info [PDF; 202 kB ; accessed on September 8, 2019]).
  12. ^ Mineral Atlas - Chernyshevsk
  13. ^ A b c Edward S. Grew, Andrew J. Locock, Stuart J. Mills, Irina O. Galuskina, Evgeny V. Galuskin, Ulf Hålenius: IMA Report - Nomenclature of the garnet supergroup . In: The American Mineralogist . tape 98 , 2013, p. 785–811 (English, cnmnc.main.jp [PDF; 2.0 MB ; accessed on September 8, 2019]).
  14. ↑ HG Huckenholz, HS Yoder: Andradite stability relations in the CaSiO 3 –Fe 2 O 3 join up to 30 Kb. In: New Yearbook for Mineralogy, Abhandlungen . tape 114 , 1971, p. 246–280 (English, htracyhall.org [PDF; 2.2 MB ; accessed on May 6, 2018]).
  15. ^ T. Isaacs: A study of uvarovite . In: Mineralogical Magazine . tape 35 , 1965, pp. 341–346 (English, rruff.info [PDF; 328 kB ; accessed on September 8, 2019]).
  16. ^ HG Huckenholz, D. Knittel: Uvarovite: Stability of uvarovite-grossularite solid solution at low pressure . In: Contributions to Mineralogy and Petrology . tape 49 , 1975, pp. 211-232 , doi : 10.1007 / BF00376589 (English).
  17. ^ Joaquín Proenza, Jesús Solé, Joan Carles Melgarejo: Uvarovite in podiform chromitite: the Moa-Baracoa ophiolitic massif, Cuba . In: The Canadian Mineralogist . tape 37 , 1999, pp. 679–690 (English, rruff.info [PDF; 3.4 MB ; accessed on September 8, 2019]).
  18. ↑ a b c Jibamitra Ganguly, Weiji Cheng, Massimiliano Tirone: Thermodynamics of alimosilicate garnet solid solution: new experimental data, an optimized model, and thermodynamic applications . In: Contributions to Mineralogy and Petrology . tape 126 , 1996, pp. 137–151 (English, researchgate.net [PDF; 1.9 MB ; accessed on September 8, 2019]).
  19. ↑ a b Liping Wang, Eric J. Essene, Youxue Zhang: Direct observation of immiscibility in pyrope-almandine-grossular garnet . In: The American Mineralogist . tape 85 , 2000, pp. 41–46 (English, researchgate.net [PDF; 401 kB ; accessed on September 8, 2019]).
  20. ↑ a b Hidehiko Shimazaki: Grosslar-Spessartine-Almandine Garnets from some Japanese Scheelite Skarns . In: The Canadian Mineralogist . tape 15 , 1977, pp. 74–80 (English, rruff.info [PDF; 602 kB ; accessed on September 8, 2019]).
  21. ↑ U. Rodehorst, MA Carpenter, T. Boffa Ballaran, CA Geiger: Local structural heterogeneity, mixing behavior and saturation effects in the grossular-spessartine solid solution . In: Physics and Chemistry of Minerals . tape 31 , 2004, p. 387–404 (English, researchgate.net [PDF; 639 kB ; accessed on September 8, 2019]).
  22. ↑ Yu Hariya, Seigo Nakano: Experimental Study of the Solid Solution between the Grossular-Almandine Series . In: Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy = 北海道 大學 理學 部 紀要 . tape 15 , 1972, p. 173–178 (English, eprints.lib.hokudai.ac.jp [PDF; 307 kB ; accessed on September 8, 2019]).
  23. ^ EP Flint, Howard F. McMurdie, Lansing S. Wells: Hydrothermal and X-ray studies of the garnet – hydrogarnet series and the relationship of the series to hydration products of Portland Cement . In: Journal of Research of the National Bureau of Standards . tape 26 , 1941, pp. 13–33 (English, rruff.info [PDF; 20.8 MB ; accessed on September 8, 2019]).
  24. ↑ 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 (French, archives-ouvertes.fr [PDF; 1,3 MB ; accessed on June 4, 2017]).
  25. ^ Claudine 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 (French, iucr.org [accessed June 4, 2017]).
  26. ↑ sytle M. Antao: Is near-endmember birefringent grossular non-cubic? New evidence from synchrotron diffraction . In: The Canadian Mineralogist . tape 51 , 2013, p. 771–784 , doi : 10.3749 / canmin.51.5.771 (English).
  27. ↑ sytle M. Antao: The mystery of birefringent garnet: is the symmetry lower than cubic? In: Powder Diffraction . tape 28 , 2013, p. 281–288 , doi : 10.1017 / S0885715613000523 (English).
  28. ↑ Thomas Fehr, Maximilian Glas, Joachim Zang: Granat. The minerals of the garnet group: precious stones, jewelry and lasers . In: garnet. The minerals of the garnet group: precious stones, jewelry and lasers (= Christian Weise [Hrsg.]: ExtraLapis . Volume 9 ). Christian Weise Verlag, 1995, ISBN 3-921656-35-4 , ISSN  0945-8492 , p. 17 .
  29. ^ Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th, revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 122 .
  30. ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (=  Dörfler Natur ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 197 .
  31. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  668 (first edition: 1891).
  32. ↑ Localities for Grossular. In: mindat.org. Hudson Institute of Mineralogy, accessed September 8, 2019 .
  33. ↑ Find location list for Grossular in the Mineralienatlas and in Mindat