Abstract: There is disclosed a fired ceramic article such as a mold or die having no surface flaws; a uniform open porosity of at least 20% by volume, average pore size in the range of 1-10 microns, high abrasion resistance, a modulus of rupture of at least 4,000 psi; the fired article being substantially the same size as the corresponding unfired article and consisting essentially of 30 to 90% by weight of refractory abrasive particles such as alumina and 70 to 10% by weight of glass particles, said glass particles containing crystals grown during firing of the article, thereby greatly increasing the strength of the article, said particles being bonded by sintering while said particles are in the solid state.