Procedures for X-Ray Diffraction Phase Analysis: The Case of Fine Sediments from Peña Blanca, Chihuahua, Mexico

In a broad project designed to examine uranium transport by surface water from Sierra Peña Blanca to Laguna del Cuervo in the Chihuahuan Desert, sediments from intermittent streams and the lagoon have been extracted and studied. Two samples were sediments from the high area of the Sierra, close to the uranium deposit “El Nopal.” Moreover, 23 core segments extracted for dating sediments were analyzed to consider changes in the fine component concentrations. The techniques of scanning electron microscopy–energy dispersive X-ray spectroscopy, XRD in a conventional diffractometer, and high-resolution synchrotron XRD analysis were applied. The crystallographic objective of the present work was to evaluate the functionality of various methodologies when applied to cases of a detailed analysis of many polyphase samples with cryptocrystals. The methods for processing the experimental data were the Rietveld method in the current multi-pattern variant of the Fullprof program and the degree of crystallinity method for the rapid estimation of the proportion of cryptocrystals in a mixture. This last technique was developed with an ad hoc software package deposited in the GitLab public repository.