The role of graphite in electrical conductivity of graphite-bearing rocks of Takkula deposit in Pälkäne, Finland

Abstract

In Finland, exploration of graphite relies on geophysical techniques and distinguishing economically viable deposits is problematic as even small quantities of conductive minerals such as graphite can significantly increase the overall electrical conductivity.

This thesis studies the role of graphite in electrical conductivity of graphite-bearing rocks. 19 graphite-bearing drill core samples from Takkula deposit are studied by combining petrography with petrophysical and geochemical analysis data to improve understanding about the role of graphite in the electrical conductivity of the rocks. In addition, 13 graphite-bearing boulder samples are studied to improve understanding of the petrophysical characteristics of graphite in boulder samples.

The results show that the contribution of graphite content to overall electrical conductivity is only moderately linear and confirm the presumptions of complex characteristics of conductivity of graphite. Graphite content adds to overall electrical conductivity, but the extent to which it can increase conductivity seems to be controlled by sulphide content and texture. In the boulder samples elevated sulphide content was associated with increased porosity and conductivity of the samples was greatly affected by textures of both sulphides and graphite flakes. The complex topic should be further researched with the aid of, for example, automated mineralogy and machine learning.