Abstract
Structural and diffraction criteria for distinguishing between t-1M, c-1M, m-1M, and 3T illite varieties are described. The t-1M illite corresponds to a one-layer monoclinic structure with vacant transsites. The c-1M illite has vacant cis-octahedra forming one of two symmetrically independent point systems; the other cis-octahedra as well as the trans-octahedra are occupied; and the m-1M illite corresponds to the structure in which cations are statistically distributed over available trans- and cis-sites. For t-1M, c-1M, and m-1M, the values of |c cos β/a| are equal to 0.39–0.41, 0.29–0.31, and 0.333, respectively. Application of these criteria demonstrates that illite samples described in the literature as the 3T polytype usually are c-1M instead. The relatively common occurrence of c-1M illite in association with t-1M and 2M1 polytypes has been recognized in illite from hydrothermal alterations around uranium deposits located in the Athabasca basement (Saskatchewan, Canada). The c-1M illite from these deposits was previously described as 3T one.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bailey, S. W. (1966) Status of clay minerals: Clays & Clay Minerals 14, 1–23.
Bailey, S. W. (1984) Crystal chemistry of the true mica: in Micas, Reviews in Mineralogy, S. W. Bailey, ed., Mineralogical Society of America, 13–60.
Beck, L. S. (1977) History of uranium exploration in Saskatchewan with special reference to changing ideas on metalogenesis: in Uranium in Saskatchewan, (DUNN C.E.) Saskatchewan Geological Society, Special Publication 3, 1–10.
Bloch, A. M., Zhukhlistov, A. P., and Zvyagin, B. B. (1990) Centrosymmetric and noncentrosymmetric sericites in the Upper Devonian of the Tuva: Abstracts of the 15th General IMA Meeting, Beijing, China 1, 297.
Brindley, G. W. and Brown, G. (1980) Crystal Structures of Clay Minerals and their X-ray Identification: Mineralogical Society, London, 2–115.
Drits, V.A. (1987) Electron Diffraction and High Resolution Electron Microscopy of Mineral Structures: Springer Verlag, Heidelberg, 301 pp.
Drits, V. A., Plançon, A., Sakharov, B. A., Besson, G., Tsipursky, S. I., and Tchoubar, C. (1984) Diffraction effects calculated for structural models of K-saturated montmorillonite containing different types of defects: Clay Miner. 19, 541–562.
Drits, V. A. and Tchoubar, C. (1990) X-ray diffraction by disordered lamellar structures: Theory and application to microdivided silicates and carbons: Springer Verlag, Heidelberg, 371 pp.
Ey, F. (1984) Un exemple de gisement d’uranium sous discordance: les mineralisations proterozoiques de Cluff Lake, Saskatchewan, Canada: Thèse Spec, Université Louis Pasteur, Strasbourg 1.
Ey, F., Gauthier-Lafaye, F., Lillie, F., and Weber, F. (1985) A uranium unconformity deposit: The geological setting of the D ore-body (Saskatchewan, Canada): in The Carswell Structure Uranium Deposits, Saskatchewan, R. Laine, D. Alonso, and M. Svab, eds., Geological Association of Canada, 29, 121–138.
Frey, M. (1987) Very low grade metamorphism of clastic sedimentary rocks: in Low temperature metamorphism, M. Frey, ed., Blackie, Glasgow, 9–58.
Gavrilov, Y. O. and Tsipursky, S. I. (1987) Clay minerals from low- and middle-Jurassic deposits of different structural and facial zones of the central Caucasus: Lithology and Raw Materials 6, 57–72 (in Russian).
Guiddotti, C. V. (1984) Micas in metamorphic rocks: in Micas, S. W. Bailey, ed., Mineralogical Society of America, Reviews in Mineralogy 13, 357–456.
Halter, G. (1988) Zonalite des alterations dans l’environement des gisements d’uranium associés à la discordance du Protérozoique moyen (Saskatchewan, Canada): Thèse doctoral, Université Louis Pasteur, Strasbourg-1.
Lonker, S. W. and Gerald, J. D. (1990) Formation of coexisting IM and 2M polytypes in illite from an active hydrothermal system: Amer. Mineral 15, 1282–1289.
Mering, J. and Oberlin, A. (1967) Electron-optical study of smectites: Clays & Clay Minerals 15, 3–25.
Pagel, M. and Svab, M. (1985) Petrographic and geochemical variations with the Carswell structure metamorphic core and their implications with respect to uranium mineralization: in The Carswell Structure Uranium Deposits of Saskatchewan, R. Laine, D. Alonso and M. Svab, eds., Geological Association of Canada, 29, 55–70.
Salyn, A. L. (1988) X-ray diffraction quantitative phase analysis of polytype and polymorph mixture: Ph.D. dissertation, Moscow State University, Moscow.
Sakharov, B. A., Besson, G., Drits, V. A., Kameneva, M. Y., Salyn, A. L., and Smolyar, B. B. (1990) X-ray study of the nature of stacking faults in the structure of glauconites: Clay Miner. 25, 419–435.
Srodon, J. and Eberl, D. D. (1984) Illite: in Micas, S. W. Bailey, ed., Mineralogical Society of America, Reviews in Mineralogy 13, 495–544.
Tsipursky, S. I. and Drits, V. A. (1984) The distribution of octahedral cations in the 2:1 layers of dioctahedral smectites studied by oblique texture electron diffraction: Clay Miner. 19, 177–192.
Warshaw, C. M. (1959) Experimental studies of illites: Clays & Clay Minerals 7, 303–316.
Yoder, H. S. and Eugster, H. P. (1955) Synthetic and natural muscovites: Geochim. Cosmochim. Acta 8, 225–280.
Zhukhlistov, A. P. and Zvyagin, B. B. (1991) The efficiency of electron diffraction in revealing 2:1 layers differing in structures and symmetry found in dioctahedral mica and smectites: in Proceedings of the 7th Euroclay Conference, Dresden, 1991, 1211–1212.
Zvyagin, B. B. (1967) Electron diffraction analysis of clay mineral structures: Plenum Press, New York.
Zvyagin, B. B., Rabotnov, V. T., Sidorenko, O. V., and Kotelnikov, D. D. (1985) Unique mica from noncentrosymmetric layers: Izvestiya Akad. Nauk SSSR, Ser. Geol. 35, 121–124 (in Russian).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Drits, V.A., Weber, F., Salyn, A.L. et al. X-Ray Identification of One-Layer Illite Varieties: Application to the Study of Illites Around Uranium Deposits of Canada. Clays Clay Miner. 41, 389–398 (1993). https://doi.org/10.1346/CCMN.1993.0410316
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1346/CCMN.1993.0410316