| abstract |
A non-photochromic colored glass containing crystals of precipitated cuprous oxide in a matrix of glass, the matrix glass consisting essentially of, in cation percent, 35-75% SiO2, 15-45% B2O3, 0-12% Al2O3, the Al2O3 being less than 10% when the SiO2 is over 55%, 0-5% ZrO2, 0-12% Li2O, 0-20% Na2O, 0-12% K2O, the sum Li2O+Na2O+K2O being 5-20%, 0-5% CaO+BaO+SrO, 0.4-1.75% Cu2O, 0-2% As2O3, 0-2% Sb2O3, 0-1% SnO2, the sum As2O3+Sb2O3+SnO2 being 0.5-2%, characterized by 0.075</=R-value </=0.65, where R-value= <IMAGE> |