¿De qué está hecho este material? Una introducción al uso e interpretación de las técnicas básicas de caracterización de los minerales

Resumo

When the mineralogical identification of a material is not possible directly, the common way to do it is using techniques such as the optical microscopy, the X-ray diffraction and the electron microscopy. Each technique is characterized by a particular preparation of samples permitting, through the interaction of different electromagnetic radiations with the material, to establish its mineralogical composition. In the case of the optical microscopy, the interaction of the visible light with the crystalline material allows to make a morphological description of the crystals and to determine optical properties, which with the help of a database, make it possible the identification. If the sample is a very fine-grained one (micrometric size) and/or inconsistent, then the most appropriate technique is the X-ray diffraction, which is based on the interaction of the X-rays with the matter. To obtain X-ray diffraction, the material must be crystalline and to interpret the X-ray diffractograms, the Bragg’s law is applied. Eventually, the databases allow to identify the mineral composition by comparison. In some cases, to determine the chemical composition of specific minerals and/or their textural relationships can be necessary and, for that, the electron microscopy, which is based on the interaction of an electron beam with the matter, is an essential tool