Jade Composition of Archaic Jade Artifact from Zeng State Tomb of the Western Zhou Dynasty in Yejiashan, Suizhou, Hubei Province

The graveyard of the Zeng State is located in the northeast part of Suizhou,Hubei Province.The graveyard was discovered in 2010, with more than 300 pieces of jade excavated.In this paper, 29 pieces of archaic jade artifacts from the Tomb M1, M3, M27, M28, M65 were comprehensively and systematically studied in terms of gemmology and petrology.The results of visual study combing with magnification observation showed that among the 29 pieces of jade samples with different colours and different degrees of soaking, 27 pieces of jade samples were nephrite, the other 2 pieces of jade samples required further testing by advanced instruments.FTIR and Raman spectrometry were used to do qualitative analysis for 29 pieces of archaic jade.27 pieces of jade samples showed the typical spectrum of tremolite in both FTIR and Raman testing, sample M28:63-FJ-1 manifested the typical spectrum of serpentinite in both FTIR and Raman spectrum.Sample M111:48-50 showed characteristic peaks of muscovite at 262, 405, 699 cm^-1 in Raman spectrun.The LA-ICP-MS was used to study chemical composition for 6 pieces of nephrite archaic jade.The major chemical composition was CaO, MgO, SiO₂,and contents were in the range of 13.55%-14.30%,23.78%-26.02% and 56.98%-58.94% respectively.The major mineral species of nephrite were calculated based on the content of Fe.Sample M65:WH-BLACK with R^* value of 0.834 was identified as actinolite (nephrite), while the other 5 pieces were tremolite (nephrite).Those 6 pieces of nephrite were all from dolomitization marble nephrite type.The SEM was used to characterize the jade structure.The etch pits at soaked part and the fibrous interlocking texture of nephrite could be obviously observed.The results presented that the large-scale test instruments could relative accurately give an index to the characteristic of jade texture with chemical composition and structure, which remedies the limitation of visual study and fundamental gemmological test.