Abstract
The effect of heat treatment and of particle orientation on the magnetic properties of granular pyrrhotite are discussed and illustrated by curves and data. Heat treatment which causes little or no chemical change alters pyrrhotite so that increased induction and remanence and decreased coercive force result. Particles aligned in a filed parallel to that used in their magnetic measurement showed greater induction and remanence but less coercive force than randomly oriented material, while cross-oriented particles showed the lowest induction and remanence but the greatest coercive force.