Comparison of laboratory and field electrical resistivity measurements of a gypsum rock for mining prospection applications

Geophysical surveys are frequently applied in mining prospection to detect the presence and volume ofore bodies of different nature. Particularly, in gypsum ore bodies exploitation, electrical resistivity mea-surements are usually the most used methodology. However, it has been observed that different electri-cal resistivity values can be obtained depending on geometrical features and composition of gypsum.Indeed, electrical resistivity of gypsum rocks depends on several parameters, such as gypsum purity, nat-ure of secondary minerals, porosity, saturation and interstitial fluid properties. Saturation and hydroge-ological setting, in particular, were recognized as the most influencing parameters. Hydrogeologicalconditions of gypsum rock masses are also very relevant for exploitability, safety conditions and eco-nomic feasibility and should be accurately known during the prospection and planning phases of thequarries. In this work, a relationship between electrical resistivity and saturation degree of gypsum isproposed. The possibility to estimate gypsum porosity with the use of this relationship is also investi-gated. The reliability of laboratory measurements is finally verified in comparison with field and mod-elled resistivity data