A glass substantially free of alkalis comprising, in mole percent on an oxide basis: SiO 2 69-72.5, Al 2 O 3 11-13.5, B 2 O 3 2.5-4.5, MgO 3-5, CaO 4-6.5, SrO 0-3, BaO 1.5-5, wherein 1.05 ≤ (MgO+CaO+SrO+BaO)/Al 2 O 3 ≤ 1.2, where SiO 2, Al 2 O 3, B 2 O 3, MgO, CaO, SrO and BaO represent the mole percents of the oxide components, with the proviso that the glass is not a glass having one of the following compositions in mole percents: SiO 2 68.96, Al 2 O 3 12.38, B 2 O 3 4.11, MgO 4.22, CaO 6.44, SrO 1.86, BaO 1.86, SnO 2 0.11, Fe 2 O 3 0.03, and ZrO 2 0.02; SiO 2 68.94, Al 2 O 3 12.38, B 2 O 3 4, MgO 4.38, CaO 6.28, SrO 2.07, BaO 1.8, SnO 2 0.11, Fe 2 O 3 0.03 and ZrO 2 0.02; SiO 2 69.39, Al 2 O 3 12.4, B 2 O 3 4.35, MgO 3.98, CaO 5.97, SrO 1.73, BaO 2.01, SnO 2 0.1, Fe 2 O 3 0.02, and ZrO 2 0.03; SiO 2 69.56, Al 2 O 3 12.35, B 2 O 3 4.23, MgO 5.03, CaO 5.42, SrO 2.1, BaO 1.17, SnO 2 0.1, Fe 2 O 3 0.02, and ZrO 2 0.02; SiO 2 69.33, Al 2 O 3 12.24, B 2 O 3 4.27, MgO 5.14, CaO 5.55, SrO 2.15, BaO 1.19, SnO 2 0.1, Fe 2 O 3 0.02 and ZrO 2 0.02; SiO 2 69.29, Al 2 O 3 12.23, B 2 O 3 4.28, MgO 5.09, CaO 5.48, SrO 2.36, BaO 1.13, SnO 2 0.1, Fe 2 O 3 0.02 and ZrO 2 0.02, SiO 2 69.24, Al 2 O 3 12.32, B 2 O 3 4.43, MgO 3.99, CaO 6.1, SrO 1.78, BaO 1.75, SnO 2 0.11, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 69.6, Al 2 O 3 12.18, B 2 O 3 4.38, MgO 3.94, CaO 6.03, SrO 1.76, BaO 1.73, SnO 2 0.11, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 68.87, Al 2 O 3 12.47, B 2 O 3 4.48, MgO 4.05, CaO 6.17, SrO 1.8, BaO 1.77, SnO 2 0.11, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 69, Al 2 O 3 12.42, B 2 O 3 4.42, MgO 3.91, CaO 6.42, SrO 1.83, BaO 1.85, SnO 2 0.11, Fe 2 O 3 0.03 and ZrO 2 0.02, SiO 2 69.05, Al 2 O 3 12.39, B 2 O 3 4.41, MgO 3.96, CaO 6.32, SrO 1.83, BaO 1.87, SnO 2 0.11, Fe 2 O 3 0.03 and ZrO 2 0.02, SiO 2 69.48, Al 2 O 3 12.4, B 2 O 3 4.35, MgO 3.96, CaO 5.77, SrO 1.67, BaO 2.22, SnO 2 0.1, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 71.23, Al 2 O 3 12.41, B 2 O 3 2.54, MgO 3.62, CaO 5.23, SrO 1.42, BaO 3.43, SnO 2 0.1, Fe 2 O 3 0.01 and ZrO 2 0.01. SiO 2 68.96, Al 2 O 3 12.38, B 2 O 3 4.11, MgO 4.22, CaO 6.44, SrO 1.86, BaO 1.86, SnO 2 0.11, Fe 2 O 3 0.03, and ZrO 2 0.02; SiO 2 68.94, Al 2 O 3 12.38, B 2 O 3 4, MgO 4.38, CaO 6.28, SrO 2.07, BaO 1.8, SnO 2 0.11, Fe 2 O 3 0.03 and ZrO 2 0.02; SiO 2 69.39, Al 2 O 3 12.4, B 2 O 3 4.35, MgO 3.98, CaO 5.97, SrO 1.73, BaO 2.01, SnO 2 0.1, Fe 2 O 3 0.02, and ZrO 2 0.03; SiO 2 69.56, Al 2 O 3 12.35, B 2 O 3 4.23, MgO 5.03, CaO 5.42, SrO 2.1, BaO 1.17, SnO 2 0.1, Fe 2 O 3 0.02, and ZrO 2 0.02; SiO 2 69.33, Al 2 O 3 12.24, B 2 O 3 4.27, MgO 5.14, CaO 5.55, SrO 2.15, BaO 1.19, SnO 2 0.1, Fe 2 O 3 0.02 and ZrO 2 0.02; SiO 2 69.29, Al 2 O 3 12.23, B 2 O 3 4.28, MgO 5.09, CaO 5.48, SrO 2.36, BaO 1.13, SnO 2 0.1, Fe 2 O 3 0.02 and ZrO 2 0.02, SiO 2 69.24, Al 2 O 3 12.32, B 2 O 3 4.43, MgO 3.99, CaO 6.1, SrO 1.78, BaO 1.75, SnO 2 0.11, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 69.6, Al 2 O 3 12.18, B 2 O 3 4.38, MgO 3.94, CaO 6.03, SrO 1.76, BaO 1.73, SnO 2 0.11, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 68.87, Al 2 O 3 12.47, B 2 O 3 4.48, MgO 4.05, CaO 6.17, SrO 1.8, BaO 1.77, SnO 2 0.11, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 69, Al 2 O 3 12.42, B 2 O 3 4.42, MgO 3.91, CaO 6.42, SrO 1.83, BaO 1.85, SnO 2 0.11, Fe 2 O 3 0.03 and ZrO 2 0.02, SiO 2 69.05, Al 2 O 3 12.39, B 2 O 3 4.41, MgO 3.96, CaO 6.32, SrO 1.83, BaO 1.87, SnO 2 0.11, Fe 2 O 3 0.03 and ZrO 2 0.02, SiO 2 69.48, Al 2 O 3 12.4, B 2 O 3 4.35, MgO 3.96, CaO 5.77, SrO 1.67, BaO 2.22, SnO 2 0.1, Fe 2 O 3 0.02 and ZrO 2 0.03, SiO 2 71.23, Al 2 O 3 12.41, B 2 O 3 2.54, MgO 3.62, CaO 5.23, SrO 1.42, BaO 3.43, SnO 2 0.1, Fe 2 O 3 0.01 and ZrO 2 0.01.