Granular compositions are disclosed for use in preparing hard, water and erosion-resistant, shapes such as foundry molds and cores, that are self-setting under ambient atmospheric conditions to allow such shapes to be stripped from patterns on which they are formed, such pattern stripping being possible immediately after forming in the case of foundry cores and the like, and within controllable pattern strip times as low as 60 seconds for foundry molds. The shapes may be used without baking and, in the case of foundry molds and cores, are ready for casting molten metal within as little as one hour. Molds and/or cores free of organic materials can be formed with the novel compositions, providing essentially carbon-free surfaces at the mold-metal interface, as well as being free of other deleterious elements such as sulfur, phosphorus and boron, thereby avoiding alloy composition alteration at the interface due to migration during casting. The refractory compositions of the invention incorporate unique aluminosilicate hydrogels of alkali metals as binders, are compatible in use with existing industrial foundry mold/core-forming equipment and procedures, and are eminently free of environmental (toxicity) problems in the foundry atmosphere.