Eberl, D. D.

Uhlík, Petr

English

Uhlík Petr

Eberl D. D.

University of Szeged

Acta Mineralogica-Petrographica, Abstract Series 5, Szeged, 2006 www.sci.u-szeged.hu/asvanytan/acta.htm 126 EVALUATION OF POWDER XRD DATA USING THE MUDMASTER AND ROCKJOCK COMPUTER PROGRAMS  UHLÍK, P.1 & EBERL, D. D.2 1 Dept. of Geology of Mineral Deposits, Comenius University, Mlynská dolina G, 842 15 Bratislava, Slovakia E-mail: uhlik@fns.uniba.sk 2 U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado, USA, 80303-1066   Powder X-ray diffraction (XRD) analysis is a fundamen-tal mineralogical method. In addition to qualitative identifica-tion of mineral phases, XRD is able to provide other impor-tant data. The presented contribution will focus on crystallite size distribution determinations and on quantitative analyses. Size distributions for crystallites can be measured by XRD because the widths of the XRD peaks broaden as crys-tallite size decreases. The MudMaster program, written by EBERL et al. (1996), calculates crystallite thickness distribu-tions (CTD) according to the Bertaut-Warren-Averbach the-ory (DRITS et al., 1998). The BWA technique has been ap-plied to measure CTD of kaolin minerals (ŠUCHA et al, 1999), to explore crystal growth mechanisms for illite and smectite (ŚRODOŃ et al., 2000; MYSTKOWSKI et al., 2000), to study diagenetic evolution of crystallite thickness distributions of illitic material (KOTARBA & ŚRODOŃ, 2000), to study weathering processes that affected smectite and illite/smectite (ŠUCHA et al., 2001), to measure funda-mental illite particle thicknesses and to study crystallite-size changes of pyrophyllite during grinding, among other appli-cations. From MudMaster analyses one is able to distinguish various geological processes. For example, thickness distri-butions of smectites show clear differences between primary bentonites and secondary, redeposited bentonites, because transport of primary bentonites decreases the mean thickness of smectite crystals. Weathering intensity is also revealed by measurement of kaolinite thickness distributions. Long and intense weathering produces thicker kaolinite crystallites than does less intensive weathering. Accurate quantitative mineral analysis is important in many scientific and applied studies. ŚRODOŃ et al. (2001) described reproducible and accurate calculation of the min-eral contents of rock by XRD when using an internal stan-dard. EBERL (2003) wrote the RockJock program based on this previous work. The program fits the sum of stored XRD patterns of standard, pure minerals (the calculated pattern) to the measured pattern by varying the fraction of each standard pattern, by using the Solver function in Microsoft Excel to minimize the degree of fit parameter between the calculated and measured pattern. One of the advantages of the program is that it contains more than 90 standards that can be used with XRD data from most diffractometers. The list of stan-dards contains common and less common minerals as well representatives of organic and volcanic matter. The program was used to determine of the quantitative mineralogical com-position of clastic sedimentary rocks, bentonites, and algi-nates with good results.  Both programs, MudMaster and RockJock, are relatively easy to use. The latest versions of this software can be ob-tained by anonymous ftp from the Internet address: ftp://brrcrftp.cr.usgs.gov/pub/ddeberl/. References DRITS, V.A., EBERL, D.D. & ŚRODOŃ, J. (1998): Clays and Clay Minerals, 46: 461–475. EBERL, D.D. (2003): U.S. Geological Survey, Open-File Report: OF 03-78, 40 p. EBERL, D.D., DRITS, V., ŚRODOŃ, J. & NÜESCH R. (1996): U.S. Geological Survey, Open-File Report: 96-171, 46 p.  KOTARBA M. & ŚRODOŃ J. (2000): Clay Minerals, 35: 383–391. MYSTKOWSKI, K., ŚRODOŃ, J. & ELSASS, F. (2000): Clay Minerals, 35: 545–557. ŚRODOŃ, J., DRITS, V., McCARTY, D.K., HSIEH, J.C.C. & EBERL, D.D. (2001): Clays and Clay Minerals, 49: 514–528. ŚRODOŃ, J., EBERL, D.D. & DRITS, V. (2000): Clays and Clay Minerals, 48: 446–458. ŠUCHA, V., KRAUS, I., ŠAMAJOVÁ, E. & PUŠKELOVÁ, L. (1999): Periodico di Mineralogia, 68: 81–92. ŠUCHA, V., ŚRODOŃ, J., CLAUER, N., ELSASS, F., EBERL, D. D., KRAUS, I. & MADEJOVA, J. (2001): Clay Minerals, 36: 403–419.  

Evaluation of powder XRD data using the mudmaster and Rockjock computer programs

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Evalution of powder XRD data using the mudmaster and Rockjock computer programs

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