Abstract: A glass ceramic composition which consists essentially of an inorganic material powder having a melting point or a glass transition point of at least 1,000° C. and a glass powder having a glass transition point of from 450 to 800° C., wherein the average of the major axes L of particles of the above inorganic material powder is from 0.5 to 15 ?m, and the average of the ratios L/W of the major axes L to the minor axes W is at most 1.4. Further, a glass ceramic composition which consists essentially of, as represented by mass percentage, from 10 to 58% of an inorganic material powder having a melting point or a glass transition point of at least 1,000° C. and from 42 to 90% of a glass powder having a glass transition point of from 450 to 800° C., wherein the glass powder consists essentially of, as represented by mol %, SiO2: 35 to 70%, B2O3: 0 to 30%, Al2O3: 3 to 18%, MgO: 0 to 40%, CaO: 0 to 19%, BaO: 0 to 35% and ZnO: 0 to 9%.

Abstract: A glass ceramic composition which consists essentially of an inorganic material powder having a melting point or a glass transition point of at least 1,000° C. and a glass powder having a glass transition point of from 450 to 800° C., wherein the average of the major axes L of particles of the above inorganic material powder is from 0.5 to 15 &mgr;m, and the average of the ratios L/W of the major axes L to the minor axes W is at most 1.4. Further, a glass ceramic composition which consists essentially of, as represented by mass percentage, from 10 to 58% of an inorganic material powder having a melting point or a glass transition point of at least 1,000° C. and from 42 to 90% of a glass powder having a glass transition point of from 450 to 800° C., wherein the glass powder consists essentially of, as represented by mol %, SiO2: 35 to 70%, B2O3: 0 to 30%, Al2O3: 3 to 18%, MgO: 0 to 40%, CaO: 0 to 19%, BaO: 0 to 35% and ZnO: 0 to 9%.

Abstract: A calcium phosphate type glass-ceramic which comprises from 64 to 72% by weight of phosphorus oxide in terms of P.sub.2 O.sub.5, from 13 to 20% by weight of calcium oxide in terms of CaO, from 6 to 13% by weight of strontium oxide in terms of SrO, and from 3 to 15% by weight in total of at least one member selected from the group consisting of aluminum oxide, cerium oxide and lanthanum oxide respectively in terms of Al.sub.2 O.sub.3, Ce.sub.2 O.sub.3 and La.sub.2 O.sub.3, a molar ratio of (CaO+SrO)/P.sub.2 O.sub.5 being 0.78-0.86.

Abstract: A mold capable of imparting uniform transparency to the calcium phosphate type crystallized glass, in which crystals of calcium metaphosphate are present at the shaping surface of the mold which comes into contact with the material to be shaped.