Magnetic fields, or regions of a magnetic field have been termed isodynamic, katadynamic or anadynamic. Force constant in magnitude throughout an isodynamic field region has proved useful in concentrating particles according to slight differences in magnetic susceptibilities. In the kata-dynamic field region the highest gradients of magnetic intensity, and consequently the greatest magnetic force can be applied to a particle. The anadynamic magnetic field region, in which the force on a particle decreases in magnitude in the direction in which field intensity increases, functions in creating a magnetic barrier at which particles of low paramagnetic or diamagnetic susceptibility can be separated. The work of S.G. Frantz Co., Inc. has been concentrated since it was founded some 40 years ago in the development and manufacture of magnetic separation equipment for mineral investigation and for industrial processing. The teaching of the Company's founder, the late Samuel G. Frantz is fundamental to today's art of magnetic separation.