An alkali-free glass consisting essentially of:

              SiO.sub.2            64 to 76 mol %,
          Al.sub.2 O.sub.3         5 to 14 mol %,
           B.sub.2 O.sub.3         5 to 16 mol %,
                 MgO               1 to 16.5 mol %,
                 CaO               0 to 14 mol %,
                 SrO               0 to 6 mol %, and
                 BaO               0 to 2 mol %.

Um vidro alcalóide-livre que consiste essencialmente em: Mol de % de SiO.sub.2 64 a 76, Al.sub.2 mol de % de O.sub.3 5 a 14, B.sub.2 mol de % de O.sub.3 5 a 16, mol de % do MgO 1 a 16.5, mol de % do CaO 0 a 14, mol de % de SrO 0 a 6, e mol de % de BaO 0 a 2.