The deeply rounded sides of this conical bowl rise gently from a circular foot toward an indented rim, covered overall with a lustrous bluish-black glaze saturated with many random silvery streaks. Both are covered with radiating silvery spots. The glaze stops short of the unfinished foot in a neat bulge above the purply-black body. The ?oil spot? effect is caused by the application of an iron-rich slip underneath the standard northern black glaze. During the bubbling and boiling of the glaze as it matures, iron oxide concentrations arose to the surface during firing. During the cooling process, these concentrations crystallized as magnetic iron oxide, which Is silvery in color. A character or symbol is impressed in the center of the foot. Northern Song Dynasty