Example: Diamond particles embeded in the sample, Mag. 500 X.
Loose abrasive particles pressed into the surface of the sample. With
soft materials, abrasive particles can become embedded. That happen
because of these reasons: Too small abrasive particle size, disc/cloth
used for grinding or polishing with too low resilience or a lubricant
with too low a viscosity. Often a combination of these reasons take place.
Reference: Metalog Guide, page 90-91,
Struers A/S, 2610 Rodovre, Dennmark.
Note: Image and text by courtesy of Struers A/S company.