Quantitative mineralogical analyses of sediments by X-ray diffraction produce erratic results because of the variety of errors involved in these determinations. Analysis of variance techniques may be used to isolate and assess major sources of error: instrumental fluctuation, differences between replicates, and inhomogeneity between replicates. Seven sample preparation techniques are compared and the most suitable techniques, suction of a water-dispersed sample onto a membrane filter and the moulding of a sample into a pellet, determined using a two-way ANOVA with replicates. Calibration charts for quartz, calcite, and dolomite may be prepared with these techniques and used as external standards for the quantitative X-ray diffraction analysis of other shale samples.

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