Specific resistivity

Electrical properties of minerals and rocks are especially important in electrical prospecting. Resistivity is inverse to conductivity, and is measured with two methods in the laboratory. Inductive conductivity measurements are performed in conjunction with susceptibility measurements on hand samples or large drill core samples. These measurements are typically suitable for samples with high conductivity, like ore samples.

Galvanic apparent resistivity is measured with a MAFRIP (frequency domain) or SCIP tester (time domain) device. In both methods, induced polarization parameters (IP values) reflecting the chargeability of the sample are calculated. The galvanic method is used for samples of low conductivity (high resistivity). Measurements give information about the permeability, which is dependent on grain size, porosity and fracturing of the rock.

Measurements can be made on both hand and drill core samples with minimum length 1 cm and maximum length 10 cm. The sample must have two parallel smoothed surfaces. Samples are kept in tap water for 3-11 days prior to measurements.