Helica owns and operates a three-directional magnetometer/gradiometer (GSMP-35A, GEM System, Canada) equipped with magnetic optically pumped potassium vapor sensors. The high performance and special configuration of the three sensors allow an optimized identification of the underground metal masses with the highest precision. This is possible thanks to both the identification of horizontal and vertical variations in the magnetic field and the precise definition of edges or contacts among the masses that generate the anomaly. Since their spatial positioning is known, these three sensors allow the assessment of the gradients for X, Y and Z in every moment during the survey.