Abstract: The process for converting feed materials of high mineral content containing primary metal values and fluorine values to the primary metal or useful compounds thereof and to fluorine values or useful compounds thereof, wherein the feed materials constitutes a difficultly soluble matrix, the process having the steps of contacting the feed materials in a reactor with a humidified, gaseous system at from about 200.degree. C. to about 1600.degree. C., the contacting being carried out such as to convert the primary metal values to oxide residues at commercially acceptable rates and to evolve gaseous fluoride from the feed, digesting said oxide residues in an acidic digest medium and separating the primary metal values from the resulting digest liquor and from other components of the residues.