Analysis Of Structure And Composition Of Ivory Unearthed From Jinsha And Sanxingdui

In order to provide the scientific basis for an effective method to protect ancient ivory unearthed from Jinsha site, the structure and composition characteristics of ancient ivory systemically and the difference between ancient and fresh ivory were analyzed and contrasted by X-ray fluorimetric analysis method, amino acid analyzer, infrared spectra, X-ray diffraction and transmission electron microscopy, the reason why the structure and composition of ancient ivory changed has been probed into. The results of research have been gained as follows.(1) The basis of ancient ivory are CaO and P₂O₅, the CaO/ P₂O₅ (Ca/ P) of ancient ivory increased, which show that the P2O5 content of ancient ivory decreased and the CaO content is increased. The amino acid content is 35.60% in fresh ivory, only 0.87% in ivory unearthed from Jinsha site and 1.13% in ivory unearthed from Sanxingdui site. (2) The main phase of ancient ivory is poor crystalline carbonate-hydroxyl-apatite. The diffraction peaks of ancient ivory were more distinct and speculate than that of the fresh ivory, and the full width at half maximum (FWHM) of the (002) peak of the ancient ivory was less than that of the fresh ivory. The hydroxyl band only appears in some ancient ivory spectra. These results show that the crystallinity of the ancient ivory was higher although it had been buried for several thousand years. (3) Ancient ivory remain some structure characteristic of ivory, for example, there also is multi- structure in cross-section of ancient ivory and the dentinal tubules; It is particular that fibril bundles hadn't been seen in microstructure of ancient ivory, which is the reason why the structure of ancient ivory is looser. There are lots of crackles in ancient ivory. The crackles have three styles such as the crackles along the circle in cross-section, radiating crackles and network crackles. (4) The big difference between the ancient ivory and the fresh ivory is that the organic composition, which plays an essential role as reinforced phase in the structure of the materials, had been eroded and destroyed. This may have been one of the reasons that ancient ivory is easily dehydrated and pulverized after it has been unearthed.