The origin of a red color glazes decorated on the ancient Jun porcelain has been attributed to the presence of combined copper clusters and cuprous oxide

or cuprous oxide alone.For better understanding of the color-forming mechanism

X-ray absorption at the Cu-edge by the red area of a Jun porcelain shard was carried out.By comparing the XANFS spectra of the sample with metal copper and cubic Cu2O

we found that the spectra of the red layer of sample were similar to the spectrum combination of 37% Cu2O and 63% metal copper

while the spectra from surface of the red spot mainly resembled that of cubic Cu2O.The EXAFS results showed that monovalence copper cations were isolated in the glaze matrix

and copper atoms were formed to metallic copper clusters or mutimers dominantly distributed in the inner layer.These can be responsible to the optical properties of the red decoration with the presence of colloidal composition containing copper particles and the Cu+ ions.In conclusion

a preliminary non-destructive elemental analysis using synchrotron radiation-induce X-ray fluorescence(SR-XRF) is demonstrated

and mechanism about the formation of the complicated structures is discussed.