As melting initiates, volatile elements are quickly released from the melt. Early in the process, the release of these volatiles may occur through small vents that leave rings of sulfur-rich phases at the surface. Small vesicles can also coalesce to form larger bubbles. Generally, as the peak temperature and duration of heating increases, the abundance of vesicles rapidly decreases. Interestingly, vitreous spherules, which are believed to form at comparatively high temperatures, often contain large and abundant vesicles. These vesicles likely formed through the evaporation of less volatile elements that require significantly higher peak temperatures.