Jade Composition of Archaic Jade Artifacts from Tomb M2011 of the Guo State in Sanmenxia,Henan Province

The graveyard of the Guo State is located on a mesa at Shangcunling of Sanmenxia, a city in the west of Henan Province.After two large-scale excavations in 1950sand 1990s, more than 250tombs and 33 000pieces (sets) of precious cultural relics were excavated.Especially, over 5 900pieces (sets) of jade and other precious stone artifacts with overall variety, fine quality, exquisite manufacture as well as their great cultural and artistic value, reflect characteristics of jade from the late Western Zhou Dynasty to the early Spring and Autumn Period.At present, these well-preserved tombs of the Guo State, where plenty of funerary objects were unearthed, seem to become increasingly important, because the tombs of the Zhou Dynasty emperors remain undiscovered.380pieces of jade have been excavated from tomb M2011which belongs to the princes of Guo State, and these jades are the objects of this study.In this paper, 26pieces of archaic jade artifacts excavated from the Tomb M2011were comprehensively and systematically studied in terms of gemmology and petrology.Firstly, material of archaic jade artifacts were observed by means of microscopic examination, magnification observation, index of refraction (IR) and density measurement, and the authors prelimiarily identified 21pieces as nephrite, 2pieces as marble and the rest 3pieces made of fine sandstone.Secondly, 6pieces of archaic jade artifacts were chosen as the samples for tests of Fourier transform infrared spectrometer (FTIR), laser Raman spectroscopy (Raman) and Xray diffraction (XRD).The M2011:457was eroded and was underwent one more test by laser erosion inductively coupled plasma mass spectrometry (LA-ICP-MS).The comprehensive analysis shows that out of the 26pieces of archaic jade artifacts, 23pieces are largely composed of nephrite and the rest 3pieces are made of fine sandstone.Raman spectroscopy examines jade at a depth of 3~4 mm, while by FTIR spectroscopy, the maximum depth from tested samples surface down is 2~3μm.The tested depth of samples at the same location was different by the two techniques.And the erosion depth of the two pieces of archaic jade artifacts, which were eroded seriously, is within the range.According to the results of the FTIR spectra and laser Raman spectra, the erosive parts did not change the main mineral components essentially. The serious erosion changes the colours of the archaic jade (stone) artifacts and decreases their luster, transparency, density and hardness, which makes a big challenge for the identification.With the help of strong transmission light, the original colours and the degree of erosion can be inferred.Besides, large equipment tests can get useful information about the changes of the texture, structure and mineral components of the archaic jade artifacts. In the 43pieces (sets) of archaic jade (stone) artifacts excavated from M2011of the Guo State, 40pieces (sets) are composed of nephrite, while the rest 3pieces (sets) are composed of fine sandstone.Nephrite was considered as the most important material at that period, while the others were just taken as colorful stones.According to the quantity and quality of the excavated archaic jade (stone) artifacts, the Tomb M2011is classified into the third class in the tombs of the Guo State, which reflects the evident social hierarchy of that period. This paper enriches the research of the excavated archaic artifacts of Henan Cultural Relic Archaeology and improves the technology content of studying archaic jade artifacts, which is beneficial to the classification, nomenclature and grading of the archaic jade artifacts.