I would look to the presence of other materials than minerals, such as soil bacteria, which are well known to have many beneficial effects. Also see my read to FF: there are anionic species undoubtedly present, but unfortunately without a full analysis of the mudballs, we cannot be certain as to what exactly was responsible.
But we do know of the meticulous way in which Dr. Price conducted his experiments, over four continents and all races of people. If inorganic minerals did have a benefit, he undoubtedly would have condoned and promoted their use.