A possible volcanic origin has been suggested for the micrometre-sized spherules that have been discovered in polar snows or ice-cores1–5, and in the stratosphere6,7. However, although such particles, especially when black and magnetic, have been identified among the tephra deposits of some volcanoes3,8–12, their volcanic emission has never been directly observed. Here we describe micro-spherules intercepted in the plume of Mount Etna, Sicily, during moderate recurring volcanic activity. Their study, using analytical transmission and scanning electron microscopy (ATEM and ASEM) demonstrates the simultaneous presence in the plume of glassy silicate microspherules of various chemical compositions (47–98% SiO2).