Patent ID: 7153795

Claim:
A transparent, translucent or opaque glass-ceramic material containing, as main crystalline phase, solid solution of β-quartz or β-spodumene, consisting essentially of the following composition, expressed as percentages by weight of oxides: 65 to 70% of SiO 2 18 to 23% of Al 2 O 3 >4 to 5% of Li 2 O 0 to <1% of MgO 1 to 3% of ZnO 0 to 2% of BaO 1.8 to 4% of TiO 2 1 to 2.5% of ZrO 2 0.4 to 1% of K 2 O and/or Na 2 O; with an effective and non-excess amount of at least one fining agent; and (ii) it has a β-OH value of higher than 0.2 mm −1 .