The instant invention relates to the production of articles exhibiting the physical properties and internal microstructure of glass-ceramic materials but which can be formed spontaneously from a molten glass, i.e., no heat treatment of a glass body to cause the crystallization in situ thereof is required, as is demanded in the manufacture of conventional glass-ceramic articles. More specifically, this invention is concerned with the production of glass-ceramic articles having compositions within the BaO-Al.sub.2 O.sub. 3 -SiO.sub.2 -F field which, when nucleated with TiO.sub.2, contain celsian (BaO.Al.sub.2 O.sub.3.2SiO.sub.2) as the predominant crystal phase, and which can be formed spontaneously from a molten glass batch.