Abstract: This invention is directed to the production of self-glazing gas-ceramic articles consisting essentially of very fine-grained cubic BPO.sub.4 crystals and very small gas-containing bubbles uniformly distributed with a SiO.sub.2 -rich residual glassy matrix, the gas within the bubbles consisting predominantly of hydrogen. The inventive articles prepared in three basic steps:(1) melting a batch for a glass consisting essentially, expressed in terms of weight percent on the oxide basis, of 30-60% SiO.sub.2, 10-40% B.sub.2 O.sub.3, 15-45% P.sub.2 O.sub.5, and up to 20% total of at least one compound in the indicated proportion selected from the group consisting of 5-15% BN, 5-10% Si, 5-10% SiC, and 10-20% Si.sub.3 N.sub.4 ;(2) cooling the melt and shaping a glass body therefrom; and(3) heating the glass body between about 900.degree.-1050.degree. C.