XRF analysis of the seated Shaka Nyorai statue of Kaniman-ji at Kyoto

The Japanese National Treasure, "Seated Shaka Nyorai bronze statue of Kaniman-ji" at Kyoto is 250.4 cm tall, weighs 2 172 kg, and is one of the largest bronze statues made by a single casting in ancient Japan. The statue was assumed to have been made over half a century between the late-7th to the mid-8th century A.D. Since the statue has been a Buddhist object of worship, no scientific research has been conducted on it to date. Fortunately, reconstruction of the hall in which the statue is housed meant that a scientific investigation of the Kaniman-ji Shaka Nyorai bronze statue could be conducted from March 2008 to June 2009. The authors investigated the chemical composition of the statue using a portable XRF spectrometer. The Kaniman-ji statue was found to be made of a copper alloy that contained arsenic, tin and lead. The composition was similar to that of Daibutsu of Todaiji. Using the analyzed data, we made an experimental cast sample to estimate the physical and mechanical properties of the alloy.