X-ray diffraction for mineral analysis of rocks and soils (XRD)

Figure 1: Three PANalytical MPD Pro for mineral analysis of rocks and special clay analysis Source: BGR

Mineral analysis of rocks and soils is performed with three PANalytical MPD Pro XRD machines (Figure 1) and one Seifert XRD 3003 TT (Figure 2). All three PANalytical machines are equipped with double detector systems; the type of detector for a given analysis can be chosen using software only. Each double detector unit contains a proportional counter which is equipped with a focused monochromator. One MPD Pro uses Cu radiation and contains a „scientific X’Cellerator“ as second detector (rock analysis, sample changer, Figure 1 on the left). The second MPD Pro uses Co radiation and contains a „scientific X’Cellerator“ as second detector (special clay mineral analysis, Figure 1 in the middle), and the third MPD Pro uses Cu radiation and contains a PIXcel detector as second detector (climate chamber CHC plus⁺, Anton Paar, 95% RH from 10 to 60 °C, Figure 1 on the right).

Figure 2: Typical evaluation of the qualitative mineral composition Source: BGR

In addition to the bulk rock analysis XRD of clays requires separation of clay fractions. After suitable disaggregation and dispersion the colloidal material is collected stepwise, homogenized and prepared on flat ceramic discs. XRD analysis of air dried and ethylene glycol solvated specimens is performed, and dependent on the analytical requirements also XRD analysis after potassium saturation, stepwise heating, etc. is used for the diagnosis of the clay minerals present.

Literature:

• Dietel, J., Gröger-Trampe J., Bertmer M., Kaufhold, S., Ufer, K., Dohrmann, R. 2019. Crystal Structure Model Development For Soil Clay Minerals – I. Hydroxy-interlayered smectite (HIS) synthesized from natural bentonite. A multianalytical study. Geoderma 347, 135–149. doi: 10.1016/j.geoderma.2019.03.021
• Dietel, J., Ufer, K., Kaufhold, S., Dohrmann, R. 2019. Crystal structure model development for soil clay minerals – II quantification and characterization of hydroxy-interlayered smectite (his) using the Rietveld refinement technique. Geoderma 347, 1–12. doi: 10.1016/j.geoderma.2019.03.020
• Dohrmann, R., Rüping, K.B., Kleber, M., Ufer, K. Jahn, R. 2009. Variation of preferred orientation in oriented clay mounts as a result of sample preparation and composition. Clays and Clay Minerals, 57(6), 686-694
• Szczerba, M., Ufer, K. 2018. New model of ethylene glycol intercalate in smectites for XRD modelling. Applied Clay Science, 153, 113–123. doi: 10.1016/j.clay.2017.12.010
• Ufer, K., Stanjek, H., Roth, G., Dohrmann, R., Kleeberg, R., Kaufhold, S. 2008. Quantitative phase analysis of bentonites by the Rietveld method. Clays and Clay Minerals 56 (2), 272-282.
• Ufer, K., Kleeberg, R., Bergmann, J., Curtius, H., Dohrmann, R. 2008. Refining realstructure parameters of disordered layer structures within the Rietveld method, Zeitschrift für Kristallographie Supplements, 27, 151-158
• Ufer, K., Kleeberg, R., Bergmann, J., Dohrmann, R. 2012. Rietveld refinement of disordered illite-smectite mixed layered structures by a recursive algorithm. I: One-dimensional patterns. Clays and Clay Minerals 60, 507–534.
• Ufer, K., Kleeberg, R., Bergmann, J., Dohrmann, R. 2012. Rietveld refinement of disordered illite/smectite mixed layered minerals with a recursive algorithm. II: powder pattern refinement and quantitative phase analysis. Clays and Clay Minerals 60, 535–552.
• Ufer, K., Kleeberg, R., Monecke, T. 2015. Quantification of stacking disordered Si-Al layer silicates by the Rietveld method: application to exploration for high-sulphidation epithermal gold deposits. Powder Diffraction, 30, Supplement S1, S111–S118. doi: 10.1017/S0885715615000111
• Ufer, K., Kleeberg, R. 2015. Parametric Rietveld refinement of coexisting disordered clay minerals. Clay Minerals, 50, 287–295, doi: 10.1180/claymin.2015.050.3.03
• Ufer, K., Raven, M. 2017. The application of the Rietveld method in the Reynolds Cup con-test. Clays and Clay Minerals, 65, 286–297. doi: 10.1346/CCMN.2017.064063
• Wang, X., Ufer, K., Kleeberg, R. 2018. Routine investigation of structural parameters of di-octahedral smectites by the Rietveld method. Applied Clay Science, 163, 257–264. doi: 10.1016/j.clay.2018.07.011
• Zeelmaekers, E., Honty, M., Derkowski, A., Ufer, K., Środoń, J., De Craen, M., Vandenberghe, N., Adriaens, R., Wouters, L. 2015. Qualitative and quantitative mineralogical composition of the Rupelian Boom Clay in Belgium. Clay Minerals, 50, 249–272. doi: 10.1180/claymin.2015.050.2.08