Hybrid package, glass ceramic substrate for the hybrid package, and composition for the glass ceramic substrate

A glass-ceramic substrate for a hybrid package, which is made of a material which comprises inorganic components consisting essentially from 61 to 91% by weight of alumina, from 5 to 30% by weight SiO.sub.2, from 3 to 20% by weight PbO, from 0 to 15% by weight of B.sub.20 3, from 0.5 to 15% by weight of an alkaline earth metal oxide and from 0 to 6% by weight of oxides of at least one of Ti, Zr and Hf, and, as a filler, from 0.05 to 10% by weight, based on the total amount of the inorganic components, of at least one oxidizing agent selected from the group consisting of chromium oxide, vanadium oxide, cerium oxide and cobalt oxide where the chromium oxide is calculated as Cr.sub.2 O.sub.3, the vanadium oxide is calculated as V.sub.2 O.sub.5, the cerium oxide is calculated as CeO.sub.2 and the cobalt oxide is calculated as CoO.