Magnetite Sphere From a Transformer Oil Sample
This is an example of a magnetite sphere typically present as a manufacturing residue in
Transmitted Circular Polarized Light and Refected Darkfield Illumination
Magnetite spheres are created by welding, torch cutting, and power grinding iron or steel. Magnetite spheres are often
hollow and so have a bulk density much less than 5.5 grams per cubic centimeter.
Significance in the Environment:
Magnetite spheres are typically a manufacturing residue. They may be introduced during rework or from nearby work if the
transformer is air-breathing.
Magnetite spheres are relatively reflective and relatively smooth. The darkfield illumination is normally reflected in a
ring pattern from the top of the particle. Magnetite is a semi-conductor and as a result will reorient the transmitted
polarized light, resulting in a bright band around the particle.