Mineralogy and Geochemistry of “Laoshan Jade” from Shandong Province, China: Implications for Petrogenesis

“Laoshan Jade” is located in the Yangkou area of Sulu UHP metamorphic belt. This first time a systematic research study performed on its conventional gemological characteristics, mineral compositions, geochemical and petrogenesis using polarized light microscope, an electron probe microanalyzer (EMPA), X-ray fluorescence spectrometer (XRF), Raman spectrometer. The characteristics are consistent with serpentine jade. It can be named serpentinite, mainly composed (antigorite), chlorite (clinochlore), magnetite. Some samples contain magnesite chromite. Only small amounts unaltered forsterite, chrysolite, diopside found poor-quality protolith peridotite. Antigorite altered from olivine. Clinochlorite diopside. Disseminated magnetite product. Unaltered olivine belong to protolith. Chromite zonal texture also belongs average temperature pressure core calculated 1348 °C 3.1 GPa, which indicates that comes mantle asthenosphere. formation edge lower than 500 °C, origin. XRF experiments show relatively rich Mg more depleted fusible elements (Al, Ca) original peridotite, indicating serpentinite has undergone certain degree partial melting. Combined EPMA results, findings this reveal peridotite subduction zone, partially melted wedge, reacted zone fluid. Pyroxene into chlorite, serpentine, magnet generated. chromite by iron-rich fluid Finally, formed.