Scanning electron microscopy and energy dispersive spectrometric microanalysis of crystalline deposits following evaporation of CO3H-, Mg2+ and Ca2+ containing aqueous solutions

This paper is the first application of scanning electron microscopy (SEM) a nd of energy dispersive selection microanalysis (EDS) to the study of natur al spa waters used as sprays in current dermatological practice; the aim wa s to relate the mineral composition of the spray to the sensitory perceptio n recorded by the patients. Crystallized deposits were first obtained on a collodion film, from two spa waters mainly containing hydrogenocarbonate, c alcium and magnesium ions, but differing by their Mg/Ca ratio. In order to understand the types of crystals formed, mineral solutions of simpler compo sition were prepared and submitted to the same process. Among the crystalli ne varieties of calcium carbonate, calcite and vaterite were characterized; aragonite could not be detected in spa waters deposits, despite the presen ce of magnesium, which favours the crystallization of this orthorhombic for m in the artificial solutions.