The Chemical Component And Indication Of Graphite Inclusions In Tremolite Jade From Sangpiyu,Liaoning

Based on the test methods such as petrography,electron probe microanalysis,cathode luminescence,X-ray powder diffraction,laser Raman spectroscopy,infrared spectroscopy,UV-visible spectroscopy and so on,the mineral composition,chemical component,spectroscopy characteristics were systematically studied in this paper and the implications for graphite inclusions were also discussed.The Sangpiyu tremolite jade shows various colours including bluish white,yellow green,deep green and dark green,although pure white variety has not yet been found.The Sangpiyu tremolite jade contains abundant graphite inclusions,mostly showing striated distribution pattern in dark green and yellow green varieties and belts of graphite in the deep green types.In dark green sample,the black belts of graphite are rather developed.Polarizing microscope reveals that the main mineral composition of the Sangpiyu tremolite jade is tremolite,with minor calcite,dolomite,zoisite,titanite,allanite,apatite and graphite.The textures of Sangpiyu tremolite jade are felt-like interweave,microfibril crystal,microscopic radial(broom)and micro-texture of crystal blade etc.The mineral grains of Sangpiyu tremolite are abundant,this suggests that tremolite jade formation process can be divided into fourth phases:platy,columnar or lamellar,fibrous and subtle fibrous.The EMPA shows that tremolite jade in Sangpiyu is predominately composed of tremolite with minor calcite,allanite,chlorite,apatite,chromite and graphite.Whereas,the major minerals of the wall rocks are plagioclase.The main chemical components of the Sangpiyu tremolite in Liaoning Province are Si O₂,Mg O and Ca O.Among them,the content of Si O₂ is generally more than 60%,and the content of Mg O and Ca O in the whole samples is slightly lower.XRD reveals that Sangpiyu tremolite is predominately composed of tremolite with minor calcite,serpentine and graphite.The graphite layers in dark green samples show a relatively constant d₍₀₀₂₎=0.33562,and suggest that these were formed at relatively high temperature metamorphic conditions.Based on the information of u and Rh%,it can further prove that the graphite inclusions in this kind of samples crystallize are much better.Raman spectroscopy of graphite inclusions shows that the D1/G intensity ratio ranges from 0.78 to 0.88 in deep green samples and from 0.05 to 0.23 in dark green samples.The ranges of D1/(D1+G)integral area ratio for these types are from0.0548 to 0.3037 and 0.5528 to 0.7355 respectively.The formation temperature of graphite inclusions in the dark green tremolite jade is computed as 549.8?,whereas that for the deep green sample is about 343.2?.Our results suggest that the jade formation occurred in a multi-stage process through the action of hydrothermal fluids and metamorphism possibly in a subduction-related setting at moderate to high temperatures.