Patent ID: 8053381

Claim:
A method for preparing a glass ceramic converted from an optically detectable, floatable arsenic- and antimony-free, glazable lithium-aluminosilicate glass that can be prestressed, comprising preparing a composition which preparation includes the addition of 0.01-0.6% by weight of Nd 2 O 3 based on oxide resulting in a composition as follows in % by weight based on oxide: SiO 2 55-69 Al 2 O 3 19-25 Li 2 O 3.2-5 Na 2 O 0-1.5 K 2 O 0-1.5 MgO 0-2.2 CaO 0-2.0 SrO 0-2.0 BaO 0-2.5 ZnO 0-<1.5 TiO 2 1-3 ZrO 2 1-2.5 SnO 2 0.1-<1 Σ TiO 2 + ZrO 2 + SnO 2 2.5-5 P 2 O 5 0-3 CoO 0.0011-0.005 F 0-1 B 2 O 3 0-2. and ceramizing.