Provided is a
cover glass having a down-drawable composition including, in
mass percent: 50%-70% SiO2, 5%-20% Al2O3, 6%-20% Na2O, 0%-10% K2O, 0%-10% MgO, above 2%-20% CaO, and 0%-4.8% ZrO2 wherein, (i) 46.5%≦(SiO2−½Al2O3)≦59%, (ii) 0.3<CaO / RO, where RO represents a total
mass percent of one or more compounds selected from the group consisting of MgO, CaO, SrO and BaO included in the glass substrate, (iii) SrO+BaO<10%, (iv) 0≦(ZrO2+TiO2) / SiO2)<0.07, and (v) 0≦B2O3 / R12O<0.1, where R12O represents a total
mass percent of one or more compounds selected from the group consisting of Li2O, Na2O and K2O included in the glass substrate.