Refining Silver: "Haifuki Cupellation Method"
The "Haifuki Method," which passes air over a mixture of lead and silver in order to sort the silver from the raw ore, was first introduced to Japan at Iwami Ginzan in 1533 by two technicians, Keiju and Sotan, who came from the Korean Peninsula at the invitation of a wealthy merchant named Kamiya Jutei from Hakata, Kyushu. This revolutionary technique dramatically improved silver refining engineering, and later spread to other mines throughout the country, including the Ikuno Silver Mine in Hyogo Prefecture and the Sado Gold and Silver Mine in Niigata Prefecture. Thus, Iwami Ginzan is referred to as the birthplace of mining technology in Japan, and the Haifuki Cupellation Method made it possible for the country to substantially increase its production of quality silver, triggering economic reform in East Asia and cultural exchanges between the East and West.
Refining Process
Step 1. Crushing
The silver ore is placed on a cornerstone and crushed using a hammer. It is then placed in water and shaken to separate the silver.
Step2. Subuki
Lead and manganese are added to fine silver ore and melted. Impurities that rise to the surface are removed creating an alloy of silver and lead.
Alloy of Silver and Lead (Property of Oda City)
Silver refined by the Haifuki Cupellation Method (Property of Oda City)
Step3. Cupellation and Refining
The alloy is placed over a bed of coals and melted. The lead sinks into the coals leaving the silver on the top. This process is repeated to increase the purity of the silver.
Oval Shaped Coin
Otoriosame-chogin (Property of the Shimane Prefecture Board of Education)
Understanding Cupellation
It has been verified through excavations that cast iron pots were used when cupellation was first introduced at the Iwami mines. This cast iron pot was unearthed at the peak of Mt. Sennoyama (470m above sea level) in remains from the days when the mine was in its infancy. It was approximately 20cm in diameter, with a lip that was used for cooking. Paving stones and iron tongs were also unearthed. Scientific analysis of the ash found stuck to the inside of the pot revealed traces of iron, manganese, lead and calcium.
Iron Pan (Property of Oda City)
Preserved State
