In this study, three clinopyroxene-enriched upper mantle xenoliths, petrographically classified as wehrlite, were investigated from the Nógrád–Gömör Volcanic Field with the use of X-ray microtomography. Our main goal was to quantify the volume of the glass phase and the vesicles to reveal their three-dimensional distribution. Among the studied wehrlite xenoliths, one is weakly and two are strongly metasomatized. The two latter wehrlite xenoliths are characterized by higher modal amount of glass and vesicles, which suggests a genetic connection between glass and concomitant vesicles, and the metasomatic agent. The glass, which was a melt at mantle conditions, forms an interconnected network. This may explain the presence of the electromagnetic anomaly with high electrical conductivity beneath the study area. Our study contributes to the better understanding of melt migration and its metasomatic effect in the lithospheric mantle beneath monogenetic volcanic fields.