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Re: Re: Re: Myth & Fact regarding nephrite jade & asbestos

Posted By: Anita Mui
Posted Date: Jan 18, 2010 (01:25 AM)

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"The geological sources of nephrite used by early cultures in China are not currently known. Such sources may have been depleted in antiquity, as nephrite can occur in small localized deposits. Research involving scientific methods on early Chinese jades has been addressing issues related to the geological origin of nephrite in early China, as well as jade production and use (Douglas, 2003). Analysis of early Chinese jades at the Freer and Sackler galleries using X-ray fluorescence spectroscopy (XRF) indicates that the geological sources of the material used for these jades are most likely associated with dolomitic marbles. The 145 jades analyzed by XRF were found to be consistently low in Cr2O3 (< 0.08 percent by wt.) and NiO (< 0.01 percent by wt.), characteristic of nephrites associated with dolomitic marbles. Future work on geological sourcing of nephrite should concentrate on these types of deposits in China.

Of particular interest are the FeO and MnO contents, which have been determined by XRF to point to simple source patterns for the nephrite used by the Neolithic cultures of Hongshan, Liangzhu, and Longshan, possibly involving one or more related geologic sources for each culture. Longshan jades were found to have unusually high FeO (0.35-17.95 percent by wt.) and MnO (0.02-0.89 percent by wt.) contents, suggesting a source particularly rich in iron and manganese. Jades of the Shang and Western Zhou dynasties show a wide range of compositions, suggesting multiple nephrite sources for these objects. XRF is a simple noninvasive tool for determining minor elemental oxide concentrations, but further work on jade sources will need to involve an expanded suite of analytical methods on a wider range of jade objects and geological samples from China."

Janet G. Douglas
Department of Conservation and Scientific Research
Freer Gallery of Art/Arthur M. Sackler Gallery
Washington, D.C.

Have fun
Anita

Link :A Review of Some Recent Research on Early Chinese Jades

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