Field-based identification of minerals using a battery-operated electrochemical measuring system with mechanical transfer of the solid to a graphite electrode

Abstract

A portable, battery-operated electrochemical instrument which enables the method of staircase voltammetry to be implemented may be coupled with the method of abrasive stripping voltammetry for the direct identification of minerals in the field. Small amounts of solid mineral samples are mechanically transferred to a paraffin-impregnated graphite electrode by rubbing the electrode against the crushed mineral. The electrode is then transferred to a conventional electrochemical cell containing electrolyte, and experiments analogous to the well known method of stripping voltammetry are then completed to provide an “electrochemical spectrum” or fingerprint of the mineral. Since the technique can be applied directly with battery-operated equipment, the method can be used by geochemists and mineralogists undertaking field work in areas remote from sophisticated laboratories and mains-powered instruments normally used to characterize minerals. The method has been successfully applied to the identification of minerals such as galena, stibnite, cuprite, pyrite and chalcopyrite, although further work is required to investigate any limitations that might apply with complex mixtures or minerals, and, at the present stage of development, the method is qualitative rather than quantitative.