To produce a beautiful patterned glass building material by heat treating the first glass spherules at a higher temperature than the softening point, thereby softening, fusing and crystallizing the first glass spherules, forming a colored ground part with an inorganic pigment in the interface between the glass spherusles and softening, fusing and integrating a pattern part prepared by softening, fusing and crystallizing the second glass spherules with the colored ground part.

This patterned crystallized glass building material is produced by heating- treating glass spherules at a higher temperature than the softening point, thereby softening, fusing and crystallizing the first glass spherules, fusing and integrating the resultant colored ground part containing a colored layer with an inorganic pigment present in the interface between the first glass spherules and fusing and integrating a patterned part prepared by softening, fusing and crystallizing the second glass spherules with the colored ground part. The glass spherules have properties of depositing needlelike crystals from the surface to the interior while softening and deforming and, e.g. those having properties of depositing β-wollastonite or diopside as main crystals are used as the glass spherules. The glass spherules mean, e.g. a pulverized material, a roughly pulverized material, a granule, powder, a sherule, a small fragment and a rodlike material. The spherules having about 0.5-10mm grain diameter are used and the first and second spherules may be mad of the same material or materials of different materials having close softening points. NiO, MnO2, etc., are used as the inorganic pigment in order to color the ground part.