Polarizing microscopy (PM), scanning electron microscopy (SEM), x-ray dispersive analysis (EDAX), x-ray diffraction (XRD), and infrared spectrometry (IR) were used to study the following pathological mineralizations: calcifications and silicon (Si)-bearing particles in cerebral tissue from an epileptic child; traces of Si-bearing paricles en periprosthesic mammarian tissue, and calcifications in capsular mammarian tissue from a patient with a silicone gel mammarian implant, and 2 calcium-bearing compounds, atypical apatitic calcification, and a nonphosphorous-bearing calcification in arterial tissues. In this tissue we also found Si-bearing particles due to an artifact from glassware.