Abstract: A process of making a porous, lightweight, insulative, inorganic container for plants having an ornamental marbleized appearance. A basic slurry formed of gypsum cement is poured into a rotating mold. While the basic slurry is being poured into the mold, one or more colored slurry mixtures are poured onto the stream of basic slurry such that the basic slurry and the colored slurry mixtures remain separated by an interface such that each stream of slurry maintains its integrity to form discrete markings of different colors in the wall of the cast container. The casting is allowed to cure for a period of 25-30 minutes in the mold at a temperature of about 70.degree. F. After the casting has been removed from the mold, it is held in a controlled atmosphere at 120.degree. F. and less than 40% relative humidity.