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Composition and genesis of albitite-hosted antecrystic pyrochlore from the Sevattur carbonatite complex, India

Part of: Alkaline rocks - Gregory Yu. Ivanyuk memorial issue

Published online by Cambridge University Press:  28 January 2021

Monojit Dey ,
Roger H. Mitchell ,
Sourav Bhattacharjee ,
Aniket Chakrabarty ,
Supriyo Pal ,
Supratim Pal  and
Amit Kumar Sen
Monojit Dey
Affiliation:
Department of Earth and Climate Science, Indian Institute of Science Education and Research Tirupati, Rami Reddy Nagar, Karakambadi Road, Mangalam, Andhra Pradesh517507, India
Roger H. Mitchell
Affiliation:
Department of Geology, Lakehead University, Thunder Bay, Ontario, CanadaP7B 5E1
Sourav Bhattacharjee
Affiliation:
Department of Earth and Climate Science, Indian Institute of Science Education and Research Tirupati, Rami Reddy Nagar, Karakambadi Road, Mangalam, Andhra Pradesh517507, India
Aniket Chakrabarty*
Affiliation:
Department of Earth and Climate Science, Indian Institute of Science Education and Research Tirupati, Rami Reddy Nagar, Karakambadi Road, Mangalam, Andhra Pradesh517507, India
Supriyo Pal
Affiliation:
Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand247667, India
Supratim Pal
Affiliation:
Department of Geology, Durgapur Government College, Durgapur, West Bengal713214, India
Amit Kumar Sen
Affiliation:
Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand247667, India
*
*Author for correspondence: Aniket Chakrabarty, Email: [email protected]; [email protected]
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Abstract

The Neoproterozoic Sevattur complex is composed essentially of calcite and dolomite carbonatites together with pyroxenites and diverse syenites. This work reports the compositions and paragenesis of different pyrochlore generations hosted by albitite veins in this complex. The pyrochlore are distinctive, being exceptionally rich in uranium (26 to 36 wt.% UO2). Five types of pyrochlore (Pcl-I to Pcl-V) are recognised on the basis of composition and texture. With the exception of Pcl-V, the majority of the pyrochlore (Pcl-II to Pcl-IV) are surrounded by a thick orbicular mantle of Ba-rich potassium feldspar. This mantle around Pcl-V is partially-broken. Pcl-I is restricted to the cores of crystals, and associated with Pcl-II and -III and is relatively rich in Nb (0.53–0.62 apfu) together with more A-site vacancies (0.37–0.71 apfu) compared to Pcl-II to Pcl-IV. Other pyrochlore (Pcl-II to Pcl-IV) are characterised by elevated Ca and Ti compared to Pcl-I, which are related to the (3Nb5+ + Na+ → 3Ti4+ + U4+) and (2Nb5+ → 2Ti4+ + Ca2+) substitutions, respectively. These substitutions represent replacement of Pcl-II to Pcl-IV. Alteration and Ba-enrichment in all the pyrochlore are marked by interaction with an externally-derived Ba-rich hydrothermal fluid following the (2Nb5+ → 2Ti4+ + Ba2+) substitution. This substitution, coupled with extensive metamictisation leads to the formation of Ba-rich (15.9–16.3 wt.% BaO) patchy-zoned Pcl-V. The orbicular mantles around Pcl-I to Pcl-IV have prevented extensive metamictisation and extensive secondary alteration compared to Pcl-V, where mantling is partially disrupted. The compositional and textural variation suggests that Pcl-II to Pcl-IV form by nucleation on Pcl-I, and are transported subsequently as antecrysts in the host albitite.

Keywords

U-rich pyrochloreorbicular mantlealbititeSevattur carbonatite
Type
Article – Gregory Yu. Ivanyuk memorial issue
Information
Mineralogical Magazine , Volume 85 , Issue 4 , August 2021 , pp. 568 - 587
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of The Mineralogical Society of Great Britain and Ireland

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Footnotes

This paper is part of a thematic set ‘Alkaline Rocks’ in memory of Dr Gregory Yu. Ivanyuk

Associate Editor: Anton R. Chakhmouradian

References

Ackerman, L., Magna, T., Rapprich, V., Upadhyay, D., Krátký, O., Čejková, B., Erban, V., Kochergina, Y.V. and Hrstka, T. (2017) Contrasting petrogenesis of spatially related carbonatites from Samalpatti and Sevattur, Tamil Nadu, India. Lithos, 284, 257–275.CrossRefGoogle Scholar
Andersen, T. (1986) Magmatic fluids in the Fen carbonatite complex, SE Norway. Contributions to Mineralogy and Petrology, 93, 491–503.CrossRefGoogle Scholar
Atencio, D., Andrade, M.B., Christy, A.G., Gieré, R. and Kartashov, P.M. (2010) The pyrochlore supergroup of minerals: nomenclature. The Canadian Mineralogist, 48, 673–698.CrossRefGoogle Scholar
Bhushan, S.K. (2015) Geology of the Kamthai rare earth deposit. Journal of the Geological Society of India, 85, 537–546.CrossRefGoogle Scholar
Bhushan, S.K. and Kumar, A. (2013) First carbonatite hosted REE deposit from India. Journal of the Geological Society of India, 81, 41–60.CrossRefGoogle Scholar
Bonazzi, P., Bindi, L., Zoppi, M., Capitani, G.C. and Olmi, F. (2006) Single-crystal diffraction and transmission electron microscopy studies of “silicified” pyrochlore from Narssârssuk, Julianehaab district, Greenland. American Mineralogist, 91, 794–801.CrossRefGoogle Scholar
Borodin, L.S., Gopal, V., Moralev, V.M., Subramanian, V. and Ponikarov, V. (1971) Precambrian carbonatites of Tamil Nadu, South India. Journal of the Geological Society of India, 12, 101–112.Google Scholar
Bosi, F., Biagioni, C. and Oberti, R. (2019) On the chemical identification and classification of minerals. Minerals, 9, 591.CrossRefGoogle Scholar
Cámara, F., Williams, C.T., Ventura, G.D., Oberti, R. and Caprilli, E. (2004) Non-metamict betafite from Le Carcarelle (Vico volcanic complex, Italy): occurrence and crystal structure. Mineralogical Magazine, 68, 939–950.CrossRefGoogle Scholar
Caprilli, E., Della Ventura, G., Williams, T.C., Parodi, G.C. and Tuccimei, P. (2006) The crystal chemistry of non-metamict pyrochlore–group minerals from Latium, Italy. The Canadian Mineralogist, 44, 1367–1378.CrossRefGoogle Scholar
Chakhmouradian, A.R. and Mitchell, R.H. (2002) New data on pyrochlore- and perovskite-group minerals from the Lovozero alkaline complex, Russia. European Journal of Mineralogy, 14, 821–836.CrossRefGoogle Scholar
Chakhmouradian, A.R., Reguir, E.P., Kressall, R.D., Crozier, J., Pisiak, L.K., Sidhu, R. and Yang, P. (2015) Carbonatite-hosted niobium deposit at Aley, northern British Columbia (Canada): Mineralogy, geochemistry and petrogenesis. Ore Geology Reviews, 64, 642–666.CrossRefGoogle Scholar
Chakrabarty, A., Mitchell, R.H., Ren, M., Saha, P.K., Pal, S., Pruseth, K.L. and Sen, A.K. (2016) Magmatic, hydrothermal and subsolidus evolution of the agpaitic nepheline syenites of the Sushina Hill Complex, India: implications for the metamorphism of peralkaline syenites. Mineralogical Magazine, 80, 1161–1193.CrossRefGoogle Scholar
Chakrabarty, A., Mitchell, R.H., Ren, M., Pal, S., Pal, S. and Sen, A.K. (2018) Nb–Zr–REE re-mobilization and implications for transitional agpaitic rock formation: insights from the Sushina Hill Complex, India. Journal of Petrology, 59, 1899–1938.Google Scholar
Chebotarev, D.A., Doroshkevich, A., Klemd, R. and Karmanov, N. (2017) Evolution of Nb-mineralization in the Chuktukon carbonatite massif, Chadobets upland (Krasnoyarsk Territory, Russia). Periodico di Mineralogia, 86, 99–118.Google Scholar
Chen, W. and Simonetti, A. (2013) In-situ determination of major and trace elements in calcite and apatite, and U–Pb ages of apatite from the Oka carbonatite complex: Insights into a complex crystallisation history. Chemical Geology, 353, 151–172.CrossRefGoogle Scholar
Christy, A.G. and Atencio, D. (2013) Clarification of status of species in the pyrochlore supergroup. Mineralogical Magazine, 77, 13–20.CrossRefGoogle Scholar
Chudy, T.C. (2013) The Petrogenesis of the Fir Carbonatite System, East-Central British Columbia, Canada. PhD dissertation, University of British Columbia, Vancouver, Canada.Google Scholar
Dostal, J. (2016) Rare metal deposits associated with alkaline/peralkaline igneous rocks. Reviews in Economic Geology, 18, 33–54.Google Scholar
Droop, G.T.R. (1987) A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria. Mineralogical Magazine, 51, 431–435.CrossRefGoogle Scholar
Dumańska-Słowik, M., Pieczka, A., Tempesta, G., Olejniczak, Z. and Heflik, W. (2014) “Silicified” pyrochlore from nepheline syenite (mariupolite) of the Mariupol Massif, SE Ukraine: A new insight into the role of silicon in the pyrochlore structure. American Mineralogist, 99, 2008–2017.CrossRefGoogle Scholar
Elliott, H.A.L., Wall, F., Chakhmouradian, A.R., Siegfried, P.R., Dahlgren, S., Weatherley, S., Finch, A.A., Marks, M.A.W., Dowman, E. and Deady, E. (2018) Fenites associated with carbonatite complexes: A review. Ore Geology Reviews, 93, 38–59.CrossRefGoogle Scholar
Essene, E.J., Claflin, C.L., Giorgetti, G., Mata, P.M., Peacor, D.R., Arkai, P. and Rathmell, M.A. (2005) Two-, three- and four-feldspar assemblages with hyalophane and celsian: implications for phase equilibria in BaAl2Si2O8–CaAl2Si2O8–NaAlSi3O8–KAlSi3O8. European Journal of Mineralogy, 17, 515–535.CrossRefGoogle Scholar
Giebel, R.J., Marks, M.A., Gauert, C.D. and Markl, G. (2019) A model for the formation of carbonatite-phoscorite assemblages based on the compositional variations of mica and apatite from the Palabora Carbonatite Complex, South Africa. Lithos, 324, 89–104.CrossRefGoogle Scholar
Giovannini, A.L., Mitchell, R.H., Neto, A.C.B., Moura, C.A., Pereira, V.P. and Porto, C.G. (2020) Mineralogy and geochemistry of the Morro dos Seis Lagos siderite carbonatite, Amazonas, Brazil. Lithos, 360, 105433.CrossRefGoogle Scholar
Harris, P.M. (1965) Pandaite from the Mrima Hill niobium deposit (Kenya). Mineralogical Magazine, 35, 277–290.CrossRefGoogle Scholar
Hatert, F. and Burke, E.A. (2008) The IMA–CNMNC dominant-constituent rule revisited and extended. The Canadian Mineralogist, 46, 717–728.CrossRefGoogle Scholar
Hawthorne, F.C., Oberti, R., Harlow, G.E., Maresch, W.V., Martin, R.F., Schumacher, J.C. and Welch, M.D. (2012) Nomenclature of the amphibole supergroup. American Mineralogist, 97, 2031–2048.CrossRefGoogle Scholar
Hogarth, D.D. (1977) Classification and nomenclature of the pyrochlore group. American Mineralogist, 62, 403–410.Google Scholar
Hogarth, D.D., Williams, C.T. and Jones, P. (2000) Primary zoning in pyrochlore group minerals from carbonatites. Mineralogical Magazine, 64, 683–697.CrossRefGoogle Scholar
Jäger, E., Niggli, E. and Van der Veen, A.H. (1959) A hydrated barium–strontium pyrochlore in a biotite rock from Panda Hill, Tanganyika 1. Mineralogical Magazine, 32, 10–25.CrossRefGoogle Scholar
Khromova, E.A., Doroshkevich, A.G., Sharygin, V.V. and Izbrodin, L.A. (2017) Compositional evolution of pyrochlore-group minerals in carbonatites of the Belaya Zima Pluton, Eastern Sayan. Geology of Ore Deposits, 59, 752–764.CrossRefGoogle Scholar
Knudsen, C. (1989) Pyrochlore Group Minerals from the Qaqarssuk Carbonatite Complex. Pp. 80–99 in: Lanthanides, Tantalum and Niobium (Möller, P., Ćerný, Petr and Saupé, Francis editors). Springer Verlag, Berlin.Google Scholar
Krishnamurthy, P. (1977) On some geochemical aspects of the Sevattur carbonatite complex, North Arcot District, Tamil Nadu. Journal of the Geological Society of India, 18, 265–274.Google Scholar
Krishnamurthy, P. (2019) Carbonatites of India. Journal of the Geological Society of India, 94, 117–138.CrossRefGoogle Scholar
Le Bas, M.J. (2008) Fenites associated with carbonatites. The Canadian Mineralogist, 46, 915–932.CrossRefGoogle Scholar
Lee, M.J., Lee, J. I., Garcia, D., Moutte, J., Williams, C.T., Wall, F. and Kim, Y. (2006) Pyrochlore chemistry from the Sokli phoscorite–carbonatite complex, Finland: implications for the genesis of phoscorite and carbonatite association. Geochemical Journal, 40, 1–13.CrossRefGoogle Scholar
Linnen, R.L. and Cuney, M. (2005) Granite–related rare–element deposits and experimental constraints on Ta–Nb–W–Sn–Zr–Hf mineralisation, in Linnen, RL and Samson, IM, eds., rare-element geochemistry and mineral deposits. Pp. 45–68 in: Rare-Element Geochemistry and Mineral Deposits, Vol. 17 (Linnen, R.L. and Samson, I.M., editors). Geological Association of Canada.Google Scholar
Linnen, R.L., Samson, I.M., Williams-Jones, A.E. and Chakhmouradian, A.R. (2014) 13.21 – Geochemistry of the rare-earth element, Nb, Ta, Hf, and Zr Deposits. Treatise on Geochemistry, 13, 543–568.CrossRefGoogle Scholar
Lumpkin, G.R. and Ewing, R.C. (1995) Geochemical alteration of pyrochlore group minerals: pyrochlore subgroup. American Mineralogist, 80, 732–743.CrossRefGoogle Scholar
Lumpkin, G.R. and Ewing, R.C. (1996) Geochemical alteration of pyrochlore group minerals: Betafite subgroup. American Mineralogist, 81, 1237–1248.CrossRefGoogle Scholar
Mackay, D.A.R. and Simandl, G.J. (2014) Geology, market and supply chain of niobium and tantalum — a review. Mineralium Deposita, 49, 1025–1047.CrossRefGoogle Scholar
Melgarejo, J.C., Costanzo, A., Bambi, A.C., Gonçalves, A.O. and Neto, A.B. (2012) Subsolidus processes as a key factor on the distribution of Nb species in plutonic carbonatites: The Tchivira case, Angola. Lithos, 152, 187–201.CrossRefGoogle Scholar
Mitchell, R.H. (2015) Primary and secondary niobium mineral deposits associated with carbonatites. Ore Geology Reviews, 64, 626–641.CrossRefGoogle Scholar
Mitchell, R.H. and Kjarsgaard, B.A. (2002) Solubility of niobium in the system CaCO3–Ca(OH)2–NaNbO3 at 0.1 GPa pressure. Contributions to Mineralogy and Petrology, 144, 93–97.CrossRefGoogle Scholar
Mitchell, R.H. and Kjarsgaard, B.A. (2004) Solubility of niobium in the system CaCO3–CaF2–NaNbO3 at 0.1 GPa pressure: implications for the crystallisation of pyrochlore from carbonatite magma. Contributions to Mineralogy and Petrology, 148, 281–287.CrossRefGoogle Scholar
Mitchell, R.H. and Smith, D.L. (2017) Geology and mineralogy of the Ashram Zone carbonatite, Eldor Complex, Québec. Ore Geology Reviews, 86, 784–806.CrossRefGoogle Scholar
Mitchell, R., Chudy, T., McFarlane, C.R. and Wu, F.Y. (2017) Trace element and isotopic composition of apatite in carbonatites from the Blue River area (British Columbia, Canada) and mineralogy of associated silicate rocks. Lithos, 286, 75–91.CrossRefGoogle Scholar
Mitchell, R.H., Wahl, R. and Cohen, A. (2020) Mineralogy and genesis of pyrochlore apatitite from The Good Hope Carbonatite, Ontario: A potential niobium deposit. Mineralogical Magazine, 84, 81–91.CrossRefGoogle Scholar
Nasraoui, M. and Bilal, E. (2000) Pyrochlores from the Lueshe carbonatite complex (Democratic Republic of Congo): a geochemical record of different alteration stages. Journal of Asian Earth Sciences, 18, 237–251.CrossRefGoogle Scholar
Naushad, Md., Murthy, P.V.R. and Cakhra, M. (2019) Barium-rich alkali feldspar in basanite from central Kachchh, north-western India. Current Science, 116, 1637.Google Scholar
Nickel, E.H. (1992) Solid solutions in mineral nomenclature. Mineralogy and Petrology, 46, 49–53.CrossRefGoogle Scholar
Nickel, E.H. and Grice, J.D. (1998) The IMA Commission on New Minerals and Mineral Names: procedures and guidelines on mineral nomenclature. Mineralogy and Petrology, 64, 237–263.CrossRefGoogle Scholar
Palmer, D.A. and Williams-Jones, A.E. (1996) Genesis of the carbonatite-hosted fluorite deposit at Amba Dongar, India; evidence from fluid inclusions, stability isotopes, and whole rock–mineral geochemistry. Economic Geology, 91, 934–950.CrossRefGoogle Scholar
Paul, D., Chandra, J. and Halder, M. (2020) Proterozoic Alkaline rocks and Carbonatites of Peninsular India: A review. Episodes Journal of International Geoscience, 43, 249–277.Google Scholar
Pouchou, J.L. and Pichoir, F. (1991) Quantitative analysis of homogeneous or stratified microvolumes applying the model “PAP”. Pp. 31–75 in: Electron probe quantitation (Heinrich, K.F.J. and Newbury, D.E., editors). Plenum Press, New York.CrossRefGoogle Scholar
Pressacco, R. (2001) Geology of the Cargill Township residual carbonatite-associated phosphate deposit, Kapuskasing, Ontario. Exploration and Mining Geology, 10, 77–84.CrossRefGoogle Scholar
Pršek, J., Ondrejka, M., Bačík, P., Budzyń, B. and Uher, P. (2010) Metamorphic-hydrothermal REE minerals in the Bacúch magnetite deposit, Western Carpathians, Slovakia:(Sr, S)-rich monazite-(Ce) and Nd-dominant hingganite. The Canadian Mineralogist, 48, 81–94.CrossRefGoogle Scholar
Raith, M.M., Devaraju, T.C. and Spiering, B. (2014) Paragenesis and chemical characteristics of the celsian – hyalophane – K-feldspar series and associated Ba–Cr micas in baryte-bearing strata of the Mesoarchaean Ghattihosahalli Belt, Western Dharwar Craton, South India. Mineralogy and Petrology, 108, 153–176.CrossRefGoogle Scholar
Ramasamy, R., Gwalani, L.G. and Subramanian, S.P. (2001) A note on the occurrence and formation of magnetite in the carbonatites of Sevvattur, North Arcot district, Tamil Nadu, Southern India. Journal of Asian Earth Sciences, 19, 297–304.CrossRefGoogle Scholar
Randive, K. and Meshram, T. (2020) An Overview of the Carbonatites from the Indian Subcontinent. Open Geosciences, 12, 85–116.CrossRefGoogle Scholar
Rukhlov, A.S. and Bell, K. (2010) Geochronology of carbonatites from the Canadian and Baltic Shields, and the Canadian Cordillera: clues to mantle evolution. Mineralogy and Petrology, 98, 11–54.CrossRefGoogle Scholar
Schleicher, H., Todt, W., Viladkar, S.G. and Schmidt, F. (1997) Pb/Pb age determinations on the Newania and Sevattur carbonatites of India: evidence for multi-stage histories. Chemical Geology, 140, 261–273.CrossRefGoogle Scholar
Schleicher, H., Kramm, U., Pernicka, E., Schidlowski, M., Schmidt, F., Subramanian, V., Todt, W. and Viladkar, S.G. (1998) Enriched subcontinental upper mantle beneath southern India: evidence from Pb, Nd, Sr, and C–O isotopic studies on Tamil Nadu carbonatites. Journal of Petrology, 39, 1765–1785.CrossRefGoogle Scholar
Schleicher, H. (2019) In-situ determination of trace element and REE partitioning in a natural apatite–carbonatite melt system using synchrotron XRF microprobe analysis. Journal of the Geological Society of India, 93, 305–312.CrossRefGoogle Scholar
Sharygin, V.V., Sobolev, N.V. and Channer, D.M.D. (2009) Oscillatory-zoned crystals of pyrochlore-group minerals from the Guaniamo kimberlites, Venezuela. Lithos, 112, 976–985.CrossRefGoogle Scholar
Starikova, A.E., Bazarova, E.P., Savel'eva, V.B., Sklyarov, E.V., Khromova, E.A. and Kanakin, S.V. (2019) Pyrochlore-group minerals in the granite-hosted Katugin rare-metal deposit, Transbaikalia, Russia. Minerals, 9, 490.CrossRefGoogle Scholar
Subramaniam, V., Viladkar, S.G. and Upendran, R. (1978) Carbonatite alkali complex of Samalpatti, Dharmapuri district, Tamil Nadu. Journal of the Geological Society of India, 19, 206–216.Google Scholar
Traversa, G., Gomes, C.B., Brotzu, P., Buraglini, N., Morbidelli, L., Principato, M.S., Ronca, S. and Ruberti, E. (2001) Petrography and mineral chemistry of carbonatites and mica-rich rocks from the Araxá complex (Alto Paranaíba Province, Brazil). Anais da Academia Brasileira de Ciências, 73, 71–98.CrossRefGoogle Scholar
Udas, G.R. and Krishnamurthy, P. (1970) Carbonatites of Sevathur and Jokipatti, Madras State, India, Proceedings of Indian National Science Academy, 36, 331–343.Google Scholar
Uher, P., Černy, P., Chapman, R., Hatar, J. and Miko, O. (1998) Evolution of Nb,Ta–oxide minerals in the Prašivá granitic pegmatites, Slovakia. II. External hydrothermal Pb, Sb overprint. The Canadian Mineralogist, 36, 535–545.Google Scholar
Verplanck, P.L., Mariano, A.N. and Mariano, A. (2016) Rare earth element ore geology of carbonatites. Reviews in Economic Geology, 18, 5–32.Google Scholar
Viladkar, S.G. and Bismayer, U. (2014) U-rich pyrochlore from Sevathur carbonatites, Tamil Nadu. Journal of the Geological Society of India, 83, 175–182.CrossRefGoogle Scholar
Viladkar, S.G. and Subramanian, V. (1995) Mineralogy and geochemistry of the carbonatites of the Sevathur and Samalpatti complexes, Tamil–Nadu. Journal of the Geological Society of India, 45, 505–517.Google Scholar
Walter, B.F., Parsapoor, A., Braunger, S., Marks, M.A.W., Wenzel, T., Martin, M. and Markl, G. (2018) Pyrochlore as a monitor for magmatic and hydrothermal processes in carbonatites from the Kaiserstuhl volcanic complex (SW Germany). Chemical Geology, 498, 1–16.CrossRefGoogle Scholar
Williams, C.T., Wall, F., Woolley, A.R. and Phillipo, S. (1997) Compositional variation in pyrochlore from the Bingo carbonatite, Zaire. Journal of African Earth Sciences, 25, 137–145.CrossRefGoogle Scholar
Zaitsev, A.N., Williams, C.T., Wall, F. and Zolotarev, A.A. (2012) Evolution of chemical composition of pyrochlore group minerals from phoscorites and carbonatites of the Khibina alkaline massif. Geology of Ore Deposits, 54, 503–515.CrossRefGoogle Scholar
Zhang, M., Suddaby, P., Thompson, R.N. and Dungan, M.A. (1993) The origins of contrasting zoning patterns in hyalophane from olivine leucitites, Northeast China. Mineralogical Magazine, 57, 565–573.CrossRefGoogle Scholar
Zurevinski, S.E. and Mitchell, R.H. (2004) Extreme compositional variation of pyrochlore-group minerals at the Oka carbonatite complex, Quebec: evidence of magma mixing? The Canadian Mineralogist, 42, 1159–1168.CrossRefGoogle Scholar