Quantitative Mineralogical Analysis by X-ray diffraction.

摘要

Work was done in two phases on different combinations of soil-like crystalline materials that were mixed in the laboratory to develop a simple, rapid, and inexpensive method of doing quantitative mineralogical analyses, largely by X-ray diffraction (XRD). In Phase I, some reference minerals of clays and nonclays of suitable purity were obtained; a method of achieving a satisfactory blend of clays and nonclays was developed; various techniques including XRD, differential thermal analysis (DTA), and infrared (IR) were evaluated; and a new method for doing a quantitative mineralogical analysis by XRD was developed and partially evaluated. The basis of this method was to prepare a pair of mixtures that match the mixture to be analyzed in composition and in background intensity and bracket it in intensity of selected XRD peaks. The range of each mineral in the bracketing mixtures was restricted, and it was assumed that there was a linear relation between amount and XRD peak intensity for each mineral. In Phase II, additional reference minerals were obtained; a system of standardizing the X-ray units by use of an external standard was put into effect, and quantitative XRD data for 87 laboratory-prepared mixtures were tabulated; and the differences in quantitative response of the same clay mineral from different sources to XRD, IR, and thermogravimetric analysis (TGA) were evaluated. Since no practical method of controlling or eliminating differences in clay minerals due to composition, grain size, crystallinity, or combinations of these factors was found, nine mixtures were analyzed by the new XRD method while permitting these variables free rein.