What characteristic distinguishes porcelain from other clay types?

Porcelain is distinguished from other types of clay primarily by its hardness, nonporous quality, and translucence. This unique set of characteristics arises from the specific mineral content in porcelain, primarily kaolin, which is fired at very high temperatures, typically above 1,200 degrees Celsius. The high firing temperature not only makes porcelain particularly strong and durable but also allows for a finer texture and a smooth finish that can become translucent.

In contrast, coarser clays are often used for stoneware or earthenware, which do not achieve the same level of translucence or hardness. Additionally, lower firing temperatures are associated with earthenware and other clay types, resulting in a porous product not found in porcelain. While porcelain can certainly be used for sculpting, this is not a defining characteristic that sets it apart from other clay types, which can also be sculpted. Thus, the defining mark of porcelain is its unique combination of hardness, nonporosity, and translucence.