Minerals from ores : visible and invisible realities

The notion of mineral resource goes far beyond the definition of a mineral: the same mineral species will have a very different value depending on its properties, while an exploitable resource may only be revealed through in-depth analysis. The first case is illustrated by the color of gems, for which the lecture analyzed the various causes of coloration. In the second case, metallic elements found in low concentrations in ores raise difficult questions as to the mechanisms of trapping during ore formation and their economic recovery. This field has benefited greatly from recent advances in the in situ analysis of trace elements in minerals. Here too, a polyhedral approach combining chemical and mineralogical vision is highly fruitful.