Crystal glass exhibiting coefficient of refraction higher than 1.53 without lead, barium and arsenic compounds

摘要

The invention relates to crystal glass having a refractive index higher than 1.53 and a high mechanical strength, free from lead compounds, barium and arsenic and guaranteeing maximum health safety, whose principle consists in that the weight consists of 55-70% SiO.sub.2 .n., 0.05 to 3.5% Li.sub.2.nO, 2-15% Na.sub.2.nO, more than 3% and less than 5% or more than 15% and less than 19 K.sub.2.nO%, 5-10% CaO, more than 1% and less than 4% or more than 7% and less than 8% of ZnO, 0.1 to 3.5% B.sub.2. nOsub.3.n., 0.1 and 3.5% Al.sub.2.nOsub.3.n., 0.1 to 3.5% TiOi2, less than 3.5 ZrOi2%, 0.05 to 1.5% Gd.sub.2.nOsub.3.n., 0.05 to 1% P.sub.2.nOsub.5.n., 0.1 to 1% Sb.sub.2.nOsub.3.n ..