Clays and Clay Minerals

, Volume 44, Issue 6, pp 835–842 | Cite as

Illite Polytype Quantification Using Wildfire© Calculated X-Ray Diffraction Patterns

  • Georg H. Grathoff
  • D. M. Moore


Illite polytype quantification allows the differentiation of diagenetic and detrital illite components. In Paleozoic shales from the Illinois Basin, we observe 3 polytypes: 1Md, 1M and 2M1. 1Md and 1M are of diagenetic origin and 2M1 is of detrital origin. In this paper, we compare experimental X-ray diffraction (XRD) traces with traces calculated using WILDFIRE© and quantify mixtures of all 3 polytypes, adjusting the effects of preferred orientation and overlapping peaks. The broad intensity (“illite hump”) around the illite 003, which is very common in illite from shales, is caused by the presence of 1Md illite and mixing of illite polytypes and is not an artifact of sample preparation or other impurities in the sample. Illite polytype quantification provides a tool to extrapolate the K/Ar age and chemistry of the detrital and diagenetic end-members by analysis of different size fractions containing different proportions of diagenetic and detrital illite polytypes.

Key Words

Cis-vacant Illite Polytypes Quantification Trans-vacant X-ray Diffraction 


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  1. Austin GS, Glass HD, Hughes RE. 1989. Resolution of the polytype structure of some illitic clay minerals that appear to be 1Md. Clays Clay Miner 37:128–134.CrossRefGoogle Scholar
  2. Bailey SW. 1966. The status of clay mineral structures. Proceedings of the 14th National Conference on Clays and Clay Minerals.New York: Pergamon Pr. p 1–23.Google Scholar
  3. Bailey SW. 1980. Structures of layer silicates. In: Brindley GW, Brown G, editors. Crystal structures of clay minerals and their X-ray identification, Monograph No. 5. London: Mineralogical Society, p 1–123.Google Scholar
  4. Bailey SW, Frank-Kamenetskii VA, Goldstaub S, Kato A, Pabst A, Schulz H, Taylor HFW, Fleischer M, Wilson AJM. 1977. International Union of Crystallography, report of the International Mineralogical Association (IMA)-International Union of Crystallography (IUCr) Joint Committee on Nomenclature. Acta Crystallogr Sect A 33:681–684.CrossRefGoogle Scholar
  5. Brown G, Brindley GW. 1980. X-ray diffraction procedures for clay mineral identification. In: Brindley GW, Brown G, editors. Crystal structures of clay minerals and their X-ray identification. Monograph No. 5. London: Mineralogical Society, p 305–359.Google Scholar
  6. Caillère S, Henin S, Rautureau M. 1982. Minéralogie des Argiles. Paris: Masson. 421 p.Google Scholar
  7. Dalla Torre M, Stern WB, Frey M. 1994. Determination of white K-mica polytype ratios: comparison of different XRD methods. Clay Miner 29:717–726.Google Scholar
  8. Drits VA, Plançon BA, Sakharov BA, Besson G, Tsipursky SI, Tchoubar C. 1984. Diffraction effects calculated for structural models of K-saturated montmorillonite containing different types of defects. Clay Miner 19:541–561.CrossRefGoogle Scholar
  9. Grathoff GH, Moore DM, Kluessendorf J, Mikulic DG. 1995. The Waukesha illite, a Silurian residuum from karstification, proposed as a candidate for the Source Clay Repository. Program with abstracts, 32nd annual Clay Minerals Society Meeting; Baltimore, Maryland; 1995 June 3–8. p 54.Google Scholar
  10. Guinier A, Bokij GB, Boll-Dornberger K, Cowley JM, Durovic S, Jagodzinski H, Krishna P, De Wolff PM, Zvyagin BB, Cox DE, Goodman P, Hahn Th, Kuchitsu K, Abrahams SC. 1984. Nomenclature of polytype structures: Report of the International Union of Crystallography Ad-Hoc Committee on the nomenclature of disordered, modulated and polytype structures. Acta Crystallogr Sect A 40:399–404.CrossRefGoogle Scholar
  11. Horton D. 1983. Argillic alteration associated with the amethyst vein system, Creede Mining District, Colorado [dissertation]. Champaign/Urbana, IL: Univ of Illinois. 337 p.Google Scholar
  12. Hower J, Hurley PM, Pinson WH, Fairbairn HW. 1963. The dependence of K-Ar age on the mineralogy of various particle size ranges in a shale. Geochim Cosmochim Acta 27: 405–410.CrossRefGoogle Scholar
  13. Hunziker JC, Frey M, Clauer N, Dallmeyer RD, Friedrichsen H, Flehmig W, Hochstrasser K, Roggwiler P, Schwander H. 1986. The evolution of illite to muscovite: mineralogical and isotopic data from the Glarus Alps, Switzerland. Contrib Mineral Petrol 92:157–180.CrossRefGoogle Scholar
  14. James RW 1965. The optical principles of the diffraction of X-rays. Vol. II of The crystalline state. Bragg, Sir L, editor. Ithaca, NY: Cornel] Univ Pr. 664 p.Google Scholar
  15. Levinson AA. 1955. Studies in the mica group: polytypism among illites and hydrous micas. Am Mineral 40:41–49.Google Scholar
  16. Maxwell DT, Hower J. 1967. High-grade diagenesis and low-grade metamorphism of illite in the Precambrian Belt Series. Am Mineral 52:843–857.Google Scholar
  17. Moore DM, Hower J. 1986. Ordered interstratification of dehydrated and hydrated Na-smectite. Clays Clay Miner 34: 379–384.CrossRefGoogle Scholar
  18. Oreskes N, Shrader-Fechette K, Belitz K. 1994. Verification, validation, and confirmation of numerical models in the earth sciences. Science 263:641–646.CrossRefGoogle Scholar
  19. Pevear DR. 1992. Illite age analysis, a new tool for basin thermal history analysis. In: Kharaka YK, Maest AS, editors. Water-rock interaction. Rotterdam, The Netherlands: AA Balkema. p 1251–1254.Google Scholar
  20. Reynolds RC, Jr. 1963. Potassium-rubidium ratios and polytypism in illites and microclines from the clay size fractions of proterozoic carbonate rocks. Geochim Cosmochim Acta 27:1097–1112.CrossRefGoogle Scholar
  21. Reynolds RC, Jr. 1985. NEWMOD©: A computer program for the calculation of one-dimensional diffraction patterns of mixed-layered clays. Hanover, NH: RC Reynolds, Jr, 8 Brook Rd.Google Scholar
  22. Reynolds RC, Jr. 1993. Three-dimensional X-ray powder diffraction from disordered illite: Simulation and interpretation of the diffraction patterns. In: Reynolds RC, Jr, Walker JR, editors. Clay Minerals Society workshop lectures, Vol 5. Computer applications to X-ray powder diffraction analysis of clay minerals. Boulder, CO: Clay Minerals Society. p 43–78.Google Scholar
  23. Reynolds RC, Jr, Thomson CH. 1993. Illite from the Potsdam sandstone of New York: A probable noncentrosymetric mica structure. Clays Clay Miner 41:66–72.CrossRefGoogle Scholar
  24. Reynolds RC, Jr. 1994. WILDFIRE©: A computer program for the calculation of three-dimensional X-ray diffraction patterns for mica polytypes and their disordered variations. Hanover, NH: RC Reynolds, Jr, 8 Brook Rd.Google Scholar
  25. Smith JV, Yoder HS, Jr. 1956. Experimental and theoretical studies of the mica polymorphs. Miner Mag 31:209–231.Google Scholar
  26. Tettenhorst RT, Corbató CE. 1993. Quantitative analysis of mixtures of IM and 2M, dioctahedral micas by X-ray diffraction. Clays Clay Miner 41:45–55.CrossRefGoogle Scholar
  27. Tsipursky SI, Drits VA. 1984. The distribution of octahedral cations in the 2:1 layers of dioctahedral smectites studied by oblique-texture electron diffraction. Clay Miner 9:177–193.CrossRefGoogle Scholar
  28. Velde B, Hower J. 1963, Petrological significance of illite polymorphism in Paleozoic sedimentary rocks. Am Mineral 48:1239–1254.Google Scholar
  29. Weaver CE, Broekstra BR. 1984. Illite-mica. In: Weaver CE et al., editors. Shale slate metamorphism in the Southern Appalachians. Developments in Petrology 10. Amsterdam: Elsevier Science, p 67–97.CrossRefGoogle Scholar

Copyright information

© The Clay Minerals Society 1996

Authors and Affiliations

  • Georg H. Grathoff
    • 1
  • D. M. Moore
    • 2
  1. 1.Department of GeologyUniversity of IllinoisUrbanaUSA
  2. 2.Illinois State Geological SurveyChampaignUSA

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