Interaction between melt inclusions and synthetic host periclase on heating

Melt inclusions in synthetic periclase, produced from natural magnesite by arc-fusion, differ in composition from that of the starting melt. They are enriched in Si, Ca, Al and Fe which are present in small amounts (up to 4-5 wt.%) in the starting melt. It is assumed that the trapping of these inclusions is intimately associated with the segregation of components which do not enter the periclase lattice at the crystallization front of the host mineral. Heating of the sample resulted in diffusive exchange of components between melt inclusions and host mineral. Diffusion of Fe from the inclusions into the matrix, and of Mg from periclase into the inclusion takes place on heating. This process starts at 950 degrees C and is considerably accelerated with the appearance of the first portions of melt (1250 degrees C).