The glass transition effect of thermal amorphized berate minerals and glasses of the same composition obtained by the cooling of the melt was studied and the influence of the origin and structural differences of the vitreous materials on the glass transition effect was considered. It has been found that thermally amorphized berates exhibit a reversible, endothermal glass transition effect which confirms their vitreous nature. The glass transition effect of amorphous berates occurs at somewhat higher temperatures and shows higher values of the apparent activation enthalpy in comparison with glasses of the same composition. It is accompanied by smaller changes of Delta c(p) in comparison with berate-like glasses obtained by melting oxide mixtures. The above dependencies are due to the differences in the middle-range order in the structure inherited from different precursors, and the method of the preparation of the glassy substance.