"All kinds of porcelain, whether round ware or vases, that have to be decorated in blue, whether modeled after that of the reigns of Xuande, Chenghua, Jiajing, or Wanli, require this blue color for the painting of their decoration.
The deep blue monochrome glaze also requires this blue for its preparation.
The material comes from the province of Chekiang, where it is found in several mountains within the prefecture's Shao-hsing Fu and Chin-hua Fu.
The collectors who go into the hills to dig for it wash away the earth that adheres to it in the water of the mountain streams. The mineral is dark brown in color. The large round pieces furnish the best blue and are called 'best rounds,' distinguished in addition by the name of the place of production.
It is brought by merchants to the porcelain manufactory, and is buried by them under the floor of the furnace roasted for three days, and washed after it is taken out, before it is finally offered for sale, ready for use.
The material is also found in different mountains in the provinces of Kiangsi [Jiangxi] and Kuangtun [Guangzhou] but the color produced by these kinds is comparatively pale and thin, and it is unable to supply the fire, so that they can be used only in painting coarse ware for sale in the market.
The picture exhibits only the collection of the material: the processes of preparation and roasting are not shown.
"
