A beryllium-magnetite correlation in the Hørtekollen-Grubeås area, Buskerud, Norway, and its use for beryllium prospection.

Abstract

A helvite-magnetite mineralization at Hørtekollen was studied for its beryllium and magnetite contents. Statistically, a close correlation between the magnetite and the beryllium contents was found to occur. Therefore a megnetic survey was made in the Hørtekollen-Grubeås area along the contact zone between the Drammen granite and the cambro-silurian metamorphic sediments in search of magnetite concentrations in which a similar relationship could exist. A well magnetic anomaly close to the surface was found, not far away from the mineralized lens of Hørtekollen. In this area, stream sediments also clearly indicate an abnormal beryllium content of more than ten to twelve times the background. Detailed magnetic measurements carried out with a nuclear procession magnetometer show that the magnetic anomaly is caused by some 1600 metric tons of magnetite. Due to its geologic setting as well as to its close proximity to the Hørtekollen mineralization, a similar relationship between magnetite and helvite can be expected to exist and this possibility warrants further investigations.