EIGHTEEN SQUARE MARBLE SLABS, apparently unpolished sections of characteristic black and white marble from the South of China, in Yunan Province, usually polished by the Chinese and mounted as dream stones to take advantage of the suggestive natural striations within the stone. Since these plaques are provisionally polished on one side only and are very thick, it is likely that they were intended to be erected as the surface finishing on the plinth of a large monument, or as the walls or floor of an important building, circa 1816