Patent ID: 7829489

Claim:
A composition for a photomachinable glass comprising: 74-81% SiO 2 , 4.5-10% Al 2 O 3 , 8.8-10.1% Li 2 O, greater than zero to less than 0.3% CeO 2 , 1.5-1.7% ZnO, 1.2-1.6% Na 2 O, 2.2-3.8% K 2 O, >0 to 0.25% Sb 2 O 3 , less than 0.1% SnO 2 , and from greater than zero up to 0.3% of at least one metal selected from the group of gold (Au) and silver (Ag), or mixtures thereof, provided that the sum of Au+Ag is not greater than 0.3%, wherein said glass has a coefficient of thermal expansion less than 6×10 −6 /° C. from 0° C. to 300° C. after heat treatment.