Skip to main content

The mystery of birefringent garnet: is the symmetry lower than cubic?

  • Sytle M. Antao (a1)

The cause of birefringence in several garnet-group minerals with general chemical formula, [8]X3 [6]Y2 [4]Z3 [4]O12, which was observed over 100 years ago, is unknown, although many different reasons were proposed, including symmetry lower than cubic. In this study, electron microprobe analyses (EMPA) were obtained for a Ti-rich andradite, ideally Ca3(Fe2 3+)Si3O12, from Magnet Cove, Arkansas, USA, and the results show that the sample is inhomogeneous with two distinct compositions. The crystal structure was refined by the Rietveld method, cubic space group $Ia\overline 3 d$ , and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data, which shows a mixture of three distinct cubic phases that are intergrown together and cause birefringence because of strain arising from small structural mismatch. This mixture of three cubic phases was not observed by any other experimental technique. These results have many implications, including garnet phase transitions from cubic to lower symmetry in the mantle, which has important geophysical consequences.

Corresponding author
a) Author to whom correspondence should be addressed. Electronic mail:
Hide All
Adamo, I., Gatta, G. D., Rotitoti, N., Diella, V., and Pavese, A. (2010). “Green andradite stones: gemological and mineralogical characterisation,” Eur. J. Miner. 23, 91100.
Agrosì, G., Schingaro, E., Pedrazzi, G., Scandale, E., and Scordari, R. (2002). “A crystal chemical insight into sector zoning of a titanian andradite (“melanite”) crystal,” Eur. J. Miner. 14, 785794.
Akaogi, M. and Akimoto, S. (1977). “Pyroxene-garnet solid-solution equilibria in the systems Mg4Si4012-Mg3Al2Si3O12 and Fe4Si4O12-Fe3Al2Si3O12 at high pressures and temperatures,” Phys. Earth Planet. Interiors 15, 90106.
Akizuki, M. (1984). “Origin of optical variations in grossular-andradite garnet,” Am. Miner. 66, 403409.
Akizuki, M., Takéuchi, Y., Terada, T., and Kudoh, Y. (1998). “Sectoral texture of a cubo-dodecahedral garnet in grandite,” Neues Jahrbuch für Mineralogie, Monatshefte 12, 565576.
Allen, F. M. and Buseck, P. R. (1988). “XRD, FTIR, and TEM studies of optically anisotropic grossular garnets,” Am. Miner. 73, 568584.
Angel, R., Finger, L. W., Hazen, R. M., Kanzaki, M., Weidner, D. J., Liebermann, R. C., and Veblen, D. R. (1989). “Structure and twinning of single-crystal MgSiO3 garnet synthesized at 17 GPa and 1800 °C,” Am. Miner. 74, 509512.
Antao, S. M. (2013). “Three cubic phases intergrown in a birefringent andradite-grossular garnet and their implications,” Phys. Chem. Miner. DOI: 10.1007/s00269-013-0606-4.
Antao, S. M. and Klincker, A. M. (2013). “Origin of birefringence in andradite from Arizona, Madagascar, and Iran,” Phys. Chem. Miner. 40, 575586.
Antao, S. M., Hassan, I., Wang, J., Lee, P. L., and Toby, B. H. (2008). “State-of-the-art high-resolution powder X-ray diffraction (HRPXRD) illustrated with Rietveld structure refinement of quartz, sodalite, tremolite, and meionite,” Can. Miner. 46, 15011509.
Antao, S. M., Klincker, A. M., and Round, S. A. (2013a). “Origin of birefringence in common silicate garnet: intergrowth of different cubic phases,” Am. Geophys. Union Conference, Cancun, Mexico, 14–17 May, 2013.
Antao, S. M., Klincker, A. M., and Round, S. A. (2013b). “Some garnets are cubic and birefringent, why?,” Conference, Hawaii, USA, 20–24 July, 2013.
Armbruster, T. (1995). “Structure refinement of hydrous andradite, Ca3Fe1.54Mn0.02Al0.26(SiO4)1.65(O4H4)1.35, from the Wessels mine, Kalahari manganese field, South Africa,” Eur. J. Miner. 7, 12211225.
Armbruster, T. and Geiger, C. A. (1993). “Andradite crystal chemistry, dynamic x-site disorder and structural strain in silicate garnets,” Eur. J. Miner. 5, 5971.
Armbruster, T. and Lager, G. A. (1989). “Oxygen disorder and the hydrogen position in garnet-hydrogarnet solid-solutions,” Eur. J. Miner. 1, 363369.
Armbruster, T., Geiger, C. A., and Lager, G. A. (1992). “Single crystal X-ray structure study of synthetic pyrope-almandine garnets at 100 and 293 K,” Am. Miner. 77, 518527.
Armbruster, T., Birrer, J., Libowitzky, E., and Beran, A. (1998). “Crystal chemistry of Ti-bearing andradites,” Eur. J. Miner. 10, 907921.
Badar, M. A., Akizuki, M., and Hussain, S. (2010). “Optical anomaly in iridescent andradite from the Sierra Madre mountains, Sonora, Mexico,” Can. Miner. 48, 11951203.
Badar, M. A., Niaz, S., Hussain, S., and Akizuki, M. (2013). “Lamellar texture and optical anomaly in andradite from the Kamaishi mine, Japan,” Eur. J. Miner. 25, 5360.
Basso, R., Dellagiusta, A., and Zefiro, L. (1981). “A crystal chemical study of a Ti-containing hydrogarnet,” Neues Jahrbuch Fur Mineralogie-Monatshefte 5, 230236.
Basso, R., Dellagiusta, A., and Zefiro, L. (1983). “Crystal-structure refinement of plazolite - a highly hydrated hatural hydrogrossular,” Neues Jahrbuch Fur Mineralogie-Monatshefte 6, 251258.
Basso, R., Cimmino, F., and Messiga, B. (1984a). “Crystal-chemistry of hydrogarnets from three different microstructural sites of a basaltic metarodingite from the Voltri-Massif (Western Liguria, Italy),” Neues Jahrbuch Fur Mineralogie-Abhandlungen 148, 246258.
Basso, R., Cimmino, F., and Messiga, B. (1984b). “Crystal chemical and petrological study of hydrogarnets from a Fe-gabbro metarodingite (Gruppo Di Voltri, Western Liguria, Italy),” Neues Jahrbuch Fur Mineralogie-Abhandlungen 150, 247258.
Bertaut, F. and Forrat, F. (1956). “Structures des ferrites ferrimagnétiques des terres rare,” C. R. Acad. Sci. 243, 382384.
Blanc, Y. and Maisonneuve, J. (1973). “Sur la biréfringence des grenats calciques,” Bull. Soc. Franç. Minér. Cristallogr. 96, 320321.
Brauns, R. (1891). Die optischen Anomalien der Kristalle. Preisschr. (Jablonowski Ges., Leipzig, Germany).
Brown, D. and Mason, R. A. (1994). “An occurrence of sectored birefringence in almandine from the Gangon terrane, Labrador,” Can. Miner. 32, 105110.
Chakhmouradian, A. R. and McCammon, C. A. (2005). “Schorlomite: a discussion of the crystal chemistry, formula, and inter-species boundaries,” Phys. Chem. Miner. 32, 277289.
Chase, A. B. and Lefever, R. A. (1960). “Birefringence of synthetic garnets,” Am. Miner. 45, 11261129.
Droop, G. T. R. (1987). “A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria,” Miner. Mag. 51, 431435.
Ferro, O., Galli, E., Papp, G., Quartieri, S., Szakall, S., and Vezzalini, G. (2003). “A new occurrence of katoite and re-examination of the hydrogrossular group,” Eur. J. Miner. 15, 419426.
Foord, E. E. and Mills, B. A. (1978). “Biaxiality in “isometric” and “dimetric” crystals,” Am. Miner. 63, 316325.
Frank-Kamenetskaya, O. V., Rozhdestvenskaya, L. V., Shtukenberg, A. G., Bannova, I. I., and Skalkina, Y. A. (2007). “Dissymmetrization of crystal structures of grossular-andradite garnets Ca3(Al, Fe)2(SiO4)3 ,” Struct. Chem. 18, 493503.
Fujino, K., Momoi, H., Sawamoto, H., and Kumazawa, M. (1986). “Crystal structure and chemistry of MnSiO3 tetragonal garnet,” Am. Miner. 71, 781785.
Ganguly, J., Cheng, W., and O'Neill, H. S. C. (1993). “Syntheses, volume, and structural changes of garnets in the pyrope-grossular join: implications for stability and mixing properties,” Am. Miner. 78, 583593.
Geiger, C. A. and Armbruster, T. (1997). “Mn3Al2Si3O12 spessartine and Ca3Al2Si3O12 grossular garnet: structural dynamic and thermodynamic properties,” Am. Miner. 82, 740747.
Geiger, C. A., Armbruster, T., Lager, G. A., Jiang, K., Lottermoser, W., and Amthauer, G. (1992). “A combined temperature dependent 57Fe Mössbauer and single crystal X-ray diffraction study of synthetic lmandine: evidence for the Gol'danskii-Karyagin effect,” Phys. Chem. Miner. 19, 121126.
Geller, S. (1967). “Crystal chemistry of garnets,” Z. Kristal 125, 147.
Geller, S. and Gilleo, M. A. (1957). “Structure and ferrimagnetism of yttrium and rare earth iron garnets,” Acta Crystallogr. 10, 239.
Geusic, J. E., Marcos, H. M., and Van Uitert, L. G. (1964). “Laser oscillations in Nd-doped yttrium aluminum, yttrium gallium and gadolinium garnets,” Appl. Phys. Lett. 4, 182184.
Gramaccioli, C. M., Pilati, T., and Demartin, F. (2002). “Atomic displacement parameters for spessartine Mn3Al2Si3O12 and their lattice-dynamical interpretation,” Acta Crystallogr. B58, 965969.
Griffen, D. T., Hatch, D. M., Phillips, W. R., and Kulaksiz, S. (1992). “Crystal chemistry and symmetry of a birefringent tetragonal pyralspite75-grandite25 garnet,” Am. Miner. 77, 399406.
Hatch, D. M. and Ghose, S. (1989). “Symmetry analysis of the phase transition and twinning in MgSiO3 garnet: implications to mantle mineralogy,” Am. Miner. 74, 12211224.
Henmi, C., Kusachi, I., and Henmi, K. (1995). “Morimotoite, Ca3TiFe2+Si3O12, a new titanian garnet from Fuka, Okayama Prefecture, Japan,” Miner. Mag. 59, 115120.
Hofmeister, A. M., Schaal, R. B., Campbell, K. R., Berry, S. L., and Fagan, T. J. (1998). “Prevalence and origin of birefringence in 48 garnets from the pyrope-almandine- grossularite-spessartine quaternary,” Am. Miner. 83, 12931301.
Ingerson, E. and Barksdale, J. D. (1943). “Iridescent garnet from the Adelaide mining district, Nevada,” Am. Miner. 28, 303312.
Ito, E. and Takahashi, E. (1987). “Ultrahigh pressure phase transformations and the constitution of the deep mantle,” in High Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto, Geophysical Monograph, edited by Manghnani, M. H. and Syono, Y., AGU, Washington, D.C. Vol. 39, pp. 221229.
Kato, T. and Kumazawa, M. (1985). “Garnet phase of MgSiO3 filling the pyroxene-ilmenite gap at very high temperature,” Nature 316, 803805.
Kingma, K. J. and Downs, J. W. (1989). “Crystal-structure analysis of a birefringent andradite,” Am. Miner. 74, 13071316.
Kitamura, K. and Komatsu, H. (1978). “Optical anisotropy associated with growth striation of yttrium garnet, Y3(Al,Fe)5O12 ,” Kristallogr. Tech. 13, 811816.
Lager, G. A., Rossman, G. R., Rotella, F. J., and Schultz, A. J. (1987a). “Neutron-diffraction structure of a low-water grossular at 20 K,” Am. Miner. 72, 766768.
Lager, G. A., Armbruster, T., and Faber, J. (1987b). “Neutron and X-ray-diffraction study of hydrogarnet Ca3Al2(O4H4)3 ,” Am. Miner. 72, 756765.
Lager, G. A., Armbruster, T., Rotella, F. J., and Rossman, G. R. (1989). “OH substitution in garnets: X-ray and neutron diffraction, infrared, and geometric-modeling studies,” Am. Miner. 74, 840851.
Larson, A. C. and Von Dreele, R. B. (2000). General Structure Analysis System (GSAS) (Report LAUR 86-748). Los Alamos National Laboratory.
Lee, P. L., Shu, D., Ramanathan, M., Preissner, C., Wang, J., Beno, M. A., Von Dreele, R. B., Ribaud, L., Kurtz, C., Antao, S. M., Jiao, X., and Toby, B. H. (2008). “A twelve-analyzer detector system for high-resolution powder diffraction,” J. Synchrotron Radiat. 15, 427432.
Lessing, P. and Standish, R. P. (1973). “Zoned garnet from Crested Butte, Colorado,” Am. Miner. 58, 840842.
Liu, L. (1977). “The system enstatite-pyrope at high pressures and temperatures and the mineralogy of the Earth's mantle,” Earth Planet. Sci. Lett. 36, 237245.
Locock, A. J. (2008). “An excel spreadsheet to recast analyses of garnet into end-member components, and a synopsis of the crystal chemistry of natural silicate garnets,” Comput. Geosci. 34, 17691780.
Munno, R., Rossi, G., and Tadini, C. (1980). “Crystal chemistry of kimzeyite from Stromboli, Aeolian Islands, Italy,” Am. Miner. 65, 188191.
Nakatsuka, A., Yoshiasa, A., Yamanaka, T., Ohtaka, O., Katsura, T., and Ito, E. (1999a). “Symmetry change of majorite solid-solution in the system Mg3Al2Si3O12-MgSiO3 ,” Am. Miner. 84, 11351143.
Nakatsuka, A., Yoshiasa, A., Yamanaka, T., and Ito, E. (1999b). “Structure refinement of a birefringent Cr-bearing majorite Mg3(Mg0.34Si0.34Al0.18Cr0.14)2Si3O12 ,” Am. Miner. 84, 199202.
Nakatsuka, A., Chaya, H., and Yoshiasa, A. (2005). “Crystal structure of single-crystal CaGeO3 tetragonal garnet synthesized at 3 GPa and 1000 °C,” Am. Miner. 90, 755757.
Novak, G. A. and Gibbs, G. V. (1971). “The crystal chemistry of the silicate garnets,” Am. Miner. 56, 17691780.
Novak, G. A. and Meyer, H. O. A. (1970). “Refinement of the crystal structure of a chrome pyrope garnet: an inclusion in natural diamond,” Am. Miner. 55, 21242127.
Parise, J. B., Wang, Y., Gwanmesia, G. D., Zhang, J., Sinelnikov, Y., Chmielowski, J., Weidner, D. J., and Liebermann, R. C. (1996). “The symmetry of garnets on the pyrope (Mg3Al2Si3O12) – majorite (MgSiO3) join,” Geophys. Res. Lett. 23, 37993802.
Peterson, R. C., Locock, A. J., and Luth, R. W. (1995). “Positional disorder of oxygen in garnet: the crystal-structure refinement of schorlomite,” Can. Miner. 33, 627631.
Prewitt, C. T. and Sleight, A. W. (1969). “Garnet-like structures of high-pressure cadmium germanate and calcium germanate,” Science 163, 386387.
Rietveld, H. M. (1969). “A profile refinement method for nuclear and magnetic structures,” J. Appl. Crystallogr. 2, 6571.
Ringwood, A. E. (1967). “The pyroxene-garnet transformation in the Earth's mantle,” Earth Planet. Sci. Lett. 2, 255263.
Rossman, G. R. and Aines, R. D. (1986). “Spectroscopy of a birefringent grossular from Asbestos, Quebec, Canada,” Am. Miner. 71, 779780.
Sacerdoti, M. and Passaglia, E. (1985). “The crystal structure of katoite and implications within the hydrogrossular group of minerals,” Bull. Miner. 108, 18.
Sawamoto, H. (1987). “Phase diagram of MgSiO3 at pressures up to 24 GPa and temperatures up to 2200 °C: phase stability and properties of tetragonal garnet,” in High Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto, Geophysical Monograph, edited by Manghnani, M. H. and Syono, Y., AGU, Washington, D.C. Vol. 39, 209219.
Schingaro, E., Scordari, F., Capitanio, F., Parodi, G., Smith, D. C., and Mottana, A. (2001). “Crystal chemistry of kimzeyite from Anguillara, Mt. Sabatini, Italy,” Eur. J. Miner. 13, 749759.
Schingaro, E., Scordari, F., Pedrazzi, G., and Malitesta, C. (2004). “Ti and Fe speciation by X-ray photoelectron spectroscopy (XPS) and mössbauer spectroscopy for a full crystal chemical characterisation of Ti-garnets from Colli Albani (Italy),” Ann. Chim. 94, 185196.
Scordari, F., Schingaro, E., and Pedrazzi, G. (1999). “Crystal chemistry of melanites from Mt. Vulture (Southern Italy),” Eur. J. Miner. 11, 855869.
Shannon, R. D. (1976). “Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides,” Acta Crystallogr. Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 32, 751767.
Shtukenberg, A. G., Punin, Y. O., Frank-Kamenetskaya, O. V., Kovalev, O. G., and Sokolov, P. B. (2001). “On the origin of anomalous birefringence in grandite garnets,” Miner. Mag. 65, 445459.
Shtukenberg, A. G., Popov, D. Y., and Punin, Y. O. (2005). “Growth ordering and anomalous birefringence in ugrandite garnets,” Miner. Mag. 69, 537550.
Smyth, J. R., Madel, R. E., McCormick, T. C., Munoz, J. L., and Rossman, G. R. (1990). “Crystal-structure refinement of a F-bearing spessartine garnet,” Am. Miner. 75, 314318.
Takéuchi, Y., Haga, N., Umizu, S., and Sato, G. (1982). “The derivative structure of silicate garnets in grandite,” Z. Kristallogr. 158, 5399.
Toby, B. H. (2001). “EXPGUI, a graphical user interface for GSAS,” J. Appl. Crystallogr. 34, 210213.
Wang, J., Toby, B. H., Lee, P. L., Ribaud, L., Antao, S. M., Kurtz, C., Ramanathan, M., Von Dreele, R. B., and Beno, M. A. (2008). “A dedicated powder diffraction beamline at the advanced photon source: commissioning and early operational results,” Rev. Sci. Instrum. 79, 085105.
Weber, H. P., Virgo, D., and Huggins, F. E. (1975). “A neutron-diffraction and 57Fe Mössbauer study of a synthetic Ti-rich garnet,” Carnegie Inst. Wash. Year Book 74, 575579.
Whitney, D. L. and Evans, B. W. (2010). “Abbreviations for names of rock-forming minerals,” Am. Miner. 95, 185187.
Wildner, M. and Andrut, M. (2001). “The crystal chemistry of birefringent natural uvarovites: part II. Single-crystal X-ray structures,” Am. Miner. 86, 12311251.
Wills, A. S. and Brown, I. D. (1999). VaList. CEA, France. This is a freely available computer program.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Powder Diffraction
  • ISSN: 0885-7156
  • EISSN: 1945-7413
  • URL: /core/journals/powder-diffraction
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed