A glass composition for chemical tempering includes oxides in wt % ranges
of: SiO.sub.2 60 to 75; Al.sub.2O.sub.3 18 to 28; Li.sub.2O 3 to 9;
Na.sub.2O 0 to 3; K.sub.2O 0 to 0.5; CaO 0 to 3; MgO 0 to 3; ZrO.sub.2 0
to 3; where MgO+CaO is 0 to 6 wt %; Al.sub.2O.sub.3+ZrO.sub.2 is 18 to 28
wt %, and Na.sub.2O+K.sub.2O is 0.05 to 3.00 wt %. The glass has a log 10
viscosity temperature in the temperature range of 1328.degree. F.
(720.degree. C.) to 1499.degree. F. (815.degree. C.); a liquidus
temperature in the temperature range of 2437.degree. F. (1336.degree. C.)
to 2575.degree. F. (1413.degree. C.), and a log 7.6 softening point
temperature in the temperature range of 1544.degree. F. (840.degree. C.)
to 1724.degree. F. (940.degree. C.). The chemically tempered glass has,
among other properties, an abraded modulus of rupture of 72 to 78 KPSI,
and a modulus of rupture of 76 to 112 KPSI.
