| abstract |
The present invention is directed to transparent, essentially haze-free glass-ceramic articles exhibiting moduli of rupture in excess of 10,000 psi which consist essentially, in weight percent, of 3-6% Li₂O, 17-23% Al₂O₃, 1-4% B₂O₃, 60-70% SiO₂, 3-6% TiO₂ and/or ZrO₂, 25-500 ppm Cr₂O₃, and 1-5 mole percent of a glass modifying oxide selected from the group consisting of 0-3% K₂O and 0-2.5% SrO and/or BaO. |