PHASE FORMATION PECULIARITIES IN ALLANITE FROM "ORTHITE DYKE" OF ANADOL DEPOSIT UNDER ANNEALING

UDC 549.618 : 549.753.1 : 548.734.3 : 548.75: 549.02 : 549.08 (477.63)

https://doi.org/10.15407/mineraljournal.39.04.042

E.E. Grechanovskaya, K.O. Ilchenko, L.I. Kanunikova, S.I. Kurylo, I.N. Herasimets

M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine

34, Acad. Palladin Ave., Kyiv, Ukraine, 03142

E-mail: e.grechanovskaya@gmail.com

PHASE FORMATION PECULIARITIES IN ALLANITE FROM "ORTHITE DYKE" OF ANADOL DEPOSIT UNDER ANNEALING

Language: Ukrainian

Mineralogical journal 2017, 39 (4): 42-57

Abstract: REE-rich epidote group mineral allanite is the main mineral-concentrator of cerium group REE on Anadol ore occurrence (Eastern Azov area, Ukrainian Shield). Its crystal chemical formula is CaREEAl2Fe[Si2O7][SiO4]O(OH). The Anadol occurrence of cerium group REE ores is represented by the vein ore body of epidote-allanite and quartz-fluorite-allanite composition ("orthite dyke"). Allanite from "orthite dyke" of the Anadol occurrence forms two varieties: allanite-1 and allanite-2, which differ in crystal morphology, the unit cell parameters and degree of iron oxidation. The chemical composition of allanite samples from epidote-amphibole-allanite metasomatites and "allanite concentrate" from "orthite dyke" of the Anadol occurrence and products of the step-by-step annealing, which are formed as a result of partial or complete destruction of its structure are investigated by the methods of X-ray analysis, electron probe microanalysis and infrared spectroscopy (IR). Investigation of the chemical composition of allanite samples showed their heterogeneity. They contain two types of the britholite inclusions, the total amount of rare earths oxides and yttrium ΣREE2O3 + Y2O3 in which varies from 59 to 62 %. Allanite in thе metasomatites is represented by the late generation of allanite-2, but in the "allanite concentrate" there are both generations. During the annealing of an allanite sample in the temperature range of 400-800 °C one can observe a significant decrease in the parameters a, b and the volume of its elementary cell V, with increase in the parameter c. This is probably due to the gradual oxidation of iron and leads to the formation of "oxyallanite" and partial destruction of its structure. Further annealing in the temperature range of 950-1050 °C leads to a partial amorphization of the allanite structure and formation of a crystalline phase which by the values of the structural parameters is close to the britholite- (La), the anionic part of which is composed only of oxygen — La9.31 [Si1.04O4]6O2. So the new phase can be called a phase with structure of oxygen-rich britholite. At the same time the contents of cerianite and hematite increase and their crystallinity increases. When the "anadol" allanite sample is annealed at a temperature of 1050 °C during the day, the amorphous phase disappears. By IR-data the newly formed high-temperature annealing phase is similar to britholite, from which it differs mainly by X-anions composition in the structure channels. It is indicated by the absence in the IR spectrum of the absorption bands of the OH groups and the lanthanum silicate La9.60(SiO4)6O2.4 with apatite structure synthesized by mechanical means. It is most probable that structural positions of X in the oxybritholite phase formed on its bases are partially populated by oxygen atoms, and a certain part of them remains vacant, which is due to thе nееd for a balance of charges. It is established that the formation of new phases that appear in then high-temperature annealing of a highly crystalline allanite sample from the "orthite dyke" of Anadol occurrence and partly metamict samples from the Azov Zr-REE deposit and the Ilmen Mountains (Urals) occurs regardless of the degree of their crystallinity. But the insignificant variability of the temperature of their formation and the ratio of adequate phases are dependent only on the features of the chemical composition of the initial samples. Our studies have shown that the thermal treatment of allanite ore, with resulting extraction of cerium oxide and phase with structure of oxygen-rich britholite with the rare earth content increased up to 63 %, can be used to enrich the ore to separate these phases.

Keywords: allanite, "orthite dyke", Anadol occurrence, unit cell, infrared spectroscopy, britholite, cerianite, hematite, quartz.

References:

  1. Belskyy, V.M., Kulchytska, H.О., Voznyak, D.K. and Grechanovskaya, E.E. (2013), Mineral. Journ. (Ukraine), Vol. 35, No. 1, Kyiv, UA, pp. 50-59.
  2. Bugaenko, L.T., Ryabykh, S.M. and Bugaenko, A.L. (2008), Bulletin of Moscow Univ., Ser. Chemistry, Vol. 49, No. 6, Moscow, RU, pp. 363-388.
  3. Grechanovskaya, E., Ilchenko, K., Kanunikova, L. and Kurylo, S. (2015), Mіneral. zb., No. 65, Vyp. 1, Lviv, UA, pp. 102-109.
  4. Lazarenko, Ye.K. and Vynar, O.M. (1975), Mineralogical dictionary, Nauk. dumka, Kyiv, UA, 772 p.
  5. Marchenko, E.Ya. (1994), Mineral. Journ. (Ukraine), Vol. 16, No. 5-6, Kyiv, UA, pp. 84-89.
  6. Melnikov, V.S., Voznyak, D.K., Grechanovskaya, E.E., Gursky, D.S., Kulchytska, H.O. and Strekozov S.N. (2000), Mineral. Journ. (Ukraine), Vol. 22, No. 1, Kyiv, UA, pp. 42-61.
  7. Melnikov, V.S., Grechanovskaya, E.E., Gruba, V.V., Kulchytska, H.O., Strekozov, S.N. and Khomenko, V.M. (2007), Mineral. Journ. (Ukraine), Vol. 29, No. 3, Kyiv, UA, pp. 14-24.
  8. Melnikov, V.S., Grechanovskaya, E.E., Yushyn, O.O., Vyshnevskyi, O.A. and Strekozov, S.N. (2012), Mіneral. zb., No. 62, Vyp. 2, Lviv, UA, pp. 128-140.
  9. Kryvdik, S.G. and Sedova, E.V. (2008), Nauch. tr. DonNTU, Ser. gor.-geol., No. 7 (135), Donetsk, UA, pp. 151-154.
  10. Panov, B.S., Ivantishin, O.M., Krivonos, V.P. and Polunovsky, R.M. (1991), Dokl. AS UkrSSR, No. 4, Kyiv, UA, pp. 97-101.
  11. Hurlbut, C.S. and Klein, C. (1982), Mineralogiya po sisteme Dena, in Povarennykh, A.S. (ed.), Nedra, Moscow, RU, pp. 151-154.
  12. Khomenko, V.M., Rede, D., Kosorukov, O.O. and Strekozov, S.N. (2013), Mineral. Journ. (Ukraine), Vol. 35, No. 3, Kyiv, UA, pp. pp. 11-26.
  13. Armbruster, T., Bonazzi, P., Akasaka, M., Bermanec, V., Chopin, C., Gierè, R., Heuss-Assbichler, S., Liebscher, A., Menchetti, S., Pan, Y. and Pasero, M. (2006), Eur. Journ. Miner., Vol. 18, No. 5, pp. 551-567. https://doi.org/10.1127/0935-1221/2006/0018-0551
  14. Bèchado, E., Julien, I., Iwata, T., Masson, O., Thomas, O., Champion, F. and Fukuda, K. (2008), J. European Ceramic Soc., Vol. 28, pp. 2717-2724. https://doi.org/10.1016/j.jeurceramsoc.2008.03.045
  15. Bonazzi, P. and Menchetti, S. (1994), Amer. Miner., Vol. 79, pp. 1176-1183.
  16. Dollase, W.A. (1971), Amer. Miner., Vol. 56, pp. 447-464.
  17. Dollase, W.A. (1973), Zeitschrift für Kristallogr., Vol. 138, pp. 41-63. https://doi.org/10.1524/zkri.1973.138.138.41
  18. Fuentes, A.F., Rodrigues-Reyna, E., Martinez-Gonsález, L.G., Maczka, M., Hanuza, J. and Amador, U. (2006), Solid State Ionics, Vol. 177, pp. 1869-1873, https://doi.org/10.1016/j.ssi.2006.02.032
  19. Hoshino, M., Kimata, M., Nishida, N., Kyono, A., Shimizu, M. and Takizawa, S. (2005), Mineral. Mag., Vol. 69, No. 4, pp. 403-423. https://doi.org/10.1180/0026461056940259
  20. Ito, J. (1968), Amer. Miner., Vol. 53, No. 3, pp. 890-906.
  21. Kartashov, P.M., Ferraris, G., Ivaldi, G., Sokolova, E.V. and McCammon, C.A. (2002), Can. Miner., Vol. 40, pp. 1641-1648. https://doi.org/10.2113/gscanmin.40.6.1641
  22. Oberti, R., Ottolini, L., Della Ventura, G. and Parodi, G.C. (2001), Amer. Miner., Vol. 86, pp. 1066-1075. https://doi.org/10.2138/am-2001-8-913
  23. (2003), International Centre for Diffraction Data, PCPDFWIN, v. 2.4, PDF-2, JCPDS-ICDD, available at: http://www.icdd.com/resources/pdj/pdj18-2.htm (Accessed 13 October 2016).
English