In situ uniaxial compression experiments are performed inside a SEM for compact vitreous SiO2 microparticles. The local structure of a plastically deformed particle is assessed spatially resolved ex situ by micro Raman spectroscopy. By application of a density calibration curve a maximum silica network densification of 11% is found only in zones slightly below the circular contact areas. The particle’s inner regions remain unaffected. Conclusions from geometric considerations indicate that the observed plasticity during compression is completely accommodated by local densification.