Patent ID: 7534734

Claim:
A glass that is substantially free of alkali metals comprising in mole percent on an oxide basis: SiO 2 : 64.0-71.0 Al 2 O 3 : 9.0-12.0 B 2 O 3 : 7.0-12.0 MgO: 1.0-3.0 CaO: 6.0-11.5 SrO: 0-2.3 BaO: 0-2.3 As 2 O 3 : 0-0.05 Sb 2 O 3 : 0-0.05 wherein: (a) the glass has an iron content expressed as Fe 2 O 3 in the range of 0.010-0.033 mole percent; and (b) the glass has a tin content expressed as SnO 2 in the range of 0.017-0.112 mole percent.