Cast limestone furniture is furniture—most commonly tables, benches, consoles, planters, and bases—made from a molded composite material that uses crushed or powdered natural limestone as a major ingredient, rather than being carved from a solid limestone slab.

Typically, crushed limestone or limestone aggregate is combined with a binder—often cement-based, polymer-based, or a proprietary resin/mineral binder—plus pigments and sometimes reinforcing materials. The mixture is poured or pressed into a mold, cured, finished, and usually sealed.

This makes it different from solid natural limestone. Natural limestone is quarried and cut directly from stone, so every slab has natural variation. Cast limestone can reproduce the appearance and texture of limestone while allowing manufacturers to control the shape, thickness, edge profile, texture, and color much more easily.

For furniture manufacturing, this is particularly useful. A manufacturer can create a mold for a round, oval, rectangular, fluted, sculptural, or thick-edge tabletop and reproduce the same design repeatedly. It can also produce substantial-looking stone furniture without necessarily using an extremely thick piece of quarried stone.

One important point is that “cast limestone” isn't one universally standardized formulation. Two suppliers may both call their material cast limestone while using very different percentages of limestone, cement, resin, fillers, reinforcement, and sealers. That can substantially affect weight, porosity, staining, cracking, UV resistance, and outdoor durability.