igneous origin for the Na in the cloud of Io

Abstract
We heated mixtures of sulfur and Na‐bearing silicates in evacuated silica glass capsules to temperatures between 600°C and 950°C. At or above 850°C, Na‐silicate glass reacts with elemental S to form a (Na,K) sulfide. Mobilization of this phase may account for the presence of Na and K on the surface of Io, and hence in the material sputtered into the Jovian magnetosphere.