[Spanish talcs for pharmaceutical use. Mineralogic, chemical composition, physico-chemical properties].

A study has been carried out on the possible pharmaceutical use of 4 spanish talcs by direct estimation of the mineral purity by means of X-ray diffraction techniques, chemical analysis and quantification of some physico-chemical properties. There is a high level of talc in the samples 2 and 4, except in the talc 1 and the talc 3, with a relatively high content of chlorides. Quartz, calcite, feldspar, smectite, inter-stratified phases, kaolinite, amphibole, muscovite and dolomite are other contaminating minerals. The negative effects of these minerals on the pharmaceutical use of the talc include changes in the physical properties (colour), in the chemical ones (contained in heavy metals) as well as in the physico-chemical ones (adsorption properties). The data concerning cation exchange capacity and total specific surface are slightly higher than those concerning the pure mineral, and this is due to the occurrence of some contaminating minerals.