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An acid-resistant glass article is provided comprising : about 25-45 wt.% SiO2; about 20-35 wt.% TiO2; less than about 5 wt.% B2O3; about 15-40 wt.% of an alkaline earth modifier selected from the group consisting of B aO, S rO, and mixtures thereof, and no greater than about 25 wt.% of an alkali-metal oxide selected from the group consisting of Na2O, K2O, and mixtures thereof. The glass article is preferably in the form of a microsphere that is adapted for use as a retroreflective element in pavement markings.