Abstract: Optical glass compositions having refractive indexes of 1.60-1.69 and Abbe numbers higher than 54 as well as with a density of less than 3.4 g/cm.sup.3, and which are distinguished in that they have good chemical stability, comprising (in percent by weight): 5-30 percent SiO.sub.2 ; 20-55 percent B.sub.2 O.sub.3 ; 13-40 percent CaO; 3-25 percent La.sub.2 O.sub.3 ; and optionally one or more of the following: up to 7 percent ZrO.sub.2, up to 2 percent TiO.sub.2, up to 9 percent Al.sub.2 O.sub.3, up to 11 percent MgO, up to 10 percent ZnO, up to 10 percent SrO, and up to 12 percent BaO.

Abstract: An optical glass with the familiar optical position of n.sub.d >1.70 and v.sub.d >22, which differs from the familiar optical glasses of the optical position due to its lower density and good chemical stability, and is composed of (in percent by weight): SiO.sub.2 25-42, TiO.sub.2 15-35, B.sub.2 O.sub.3 0.5-7, BaO 3-13, CaO 1-3, Nb.sub.2 O.sub.5 1-20, GeO.sub.2 0-2, Al.sub.2 O.sub.3 0-4, Na.sub.2 O 7.5-15, Li.sub.2 O 0-9, K.sub.2 O 2-10, SrO 0-6, ZnO 0-5, ZrO.sub.2 0-3, and WO.sub.3 0-3.