X-Ray Identification of One-Layer Illite Varieties: Application to the Study of Illites Around Uranium Deposits of Canada

Abstract

Abstract--Structural and diffraction criteria for distinguishing between t-1 M, 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-lM 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-lM illite corresponds to the structure in which cations are statistically distributed over available trans-and cis-sites. For t-lM, c-lM, and m-lM, the values of Ic cos #/al 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-lM instead. The relatively common occurrence ofc-lM 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.

Three-Dimensional Crystal Structures of Illite-Smectite Minerals in Paleozoic K-Bentonites from the Appalachian Basin

“…The differences in their diffraction patterns between 20 = 20-35 ~ are evident, which demonstrates that these two structures can be confidently identified. Drits et al (1993) noted that the 3T and cv-lM structures produce similar diffraction effects. However, Reynolds and Thomson (1993) found that in determining the structure of the Potsdam illite, the d values of the Potsdam illite could not be reconciled with a hexagonal structure (e.g., 337) and these values are (1984).…”

“…The cis-vacant structure is assumed here because there are at least two reported cv illite occurrences that are well documented (Drits et al, 1993;Reynolds and Thomson, 1993) and because electron diffraction studies have reported the common occurrence of the cisvacant structure in smectites , The present study developed from efforts to identify the geological parameters that control the occurrence of tv and cv illite layer types. In the survey of McCarty (1993) of K-bentonites that encompass a wide range in ages and locations, the only convincing correlation noted was between illite layer type and location along the southwest/northeast strike of the Appalachian fold belt.…”

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

“…The than a pressure effect (e.g., Sassi and Scolari, 1974;Guidotti and Sassi, 1986 (Shirozu and Higashi, 1972;Meunier and Velde, 1982;Inoue et al, 1987Inoue et al, , 1988Drits et al, 1993;Inoue and Kitagawa, 1994;Drews-Armitage et al, 1996;Celik et al, 1999;Yan et al, 2001;Bove et al, 2002;Schleicher, 2006).…”

Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopies

“…In accordance with the diffraction features for dioctahedral tv 1M mica, XRD patterns contain strong lli, 112 and 112 reflections, whereas the 111 reflection has zero intensity. (Drits et al, 1993a).…”

“…Drits et al (1984a) formulated structural and diffraction criteria to distinguish between dioctahedral 1M micas consisting of cis-vacant (cv 1M) or trans-vacant (tv 1M) 2:1 layers. Based on these criteria, cv 1M illites were found in different geological environments (Zvyagin et al, 1985;Drits et al, 1993a;Reynolds & Thompson, 1993). Conversely, Sakharov et al, (1990) andDrits et al (1993b) studied a large collection of glauconites differing in chemical composition, age, location and structural perfection.…”