STANDARD DIAGRAMS OF MAGNETIC-PROPERTIES AND DENSITY - A TOOL FOR UNDERSTANDING MAGNETIC PETROLOGY

Bivariate diagrams of magnetic susceptibility, density, remanent magnetization and Q-ratio displaying the variation patterns from 7384 rock samples are used to demonstrate the natural variation fields of these properties of paramagnetic minerals, magnetite, pyrrhotite, and hematite. These minerals represent the most frequent source of magnetic anomalies and the variation of their content provides a definite link between lithology, geological processes, and anomalies in gravity and magnetic measurements. The magnetic susceptibility of ferrimagnetic pyrrhotite is determined empirically from the variation trend in a density-susceptibility diagram of pyrrhotite-containing rocks.