Magnetite Sphere From a Transformer Oil Sample
This is an example of a magnetite sphere typically present
as a manufacturing residue in
transformers.
Transmitted Circular Polarized Light and Refected Darkfield Illumination
Definition/Function:
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.
Characteristic Features:
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.
Associated Particles:
References:
