Mineralogical Characteristics And Genesis Of Fushan Epidote In Handan Region, Southern Taihang

The epidote is one of the main rock-forming minerals of skarn which is at Fushan skarn in the Han-Xing area of the southern Taihang Mountains.These samples were taken from the veins of the contact zone between the central Fushan intrusion and the Middle Ordovician carbonate rocks.In this paper,10 epidote samples were selected to text the mineralogical characteristics of gemstones.The crystal form of epidote grows well and can find the crystal plane longitudinal grain upgrowth.Color distribution is nonuniform,mostly show green to dark green,polychromatic strong;crack upgrowth,most samples are translucent to opaque;refractive index is 1.730 to 1.775;density is 3.21 to 3.41;hardness is 6 to 7.Fluorescent inert.Observed by polarizing microscope,epidote has larger particles and obvious zonal texture.It can be combined with other minerals with straight boundary.Other minerals are mainly small-sized calcite,chlorite,diopside,and so on.Most of them are irregular granular,flaky,radial,wormlike and so on.Electron probe analysis shows that the iron content of epidote is generally higher,but the trace element content is less.The zonal texture of epidote is formed by the difference of the enrichment of Al and Fe.According to the test results,the standardized chemical formula of epidote and the XFe value of the zonal texture were calculated.The edge of the zonal texture of epidote has higher XFe value.The standardized chemical formula of epidote in Fushan is Ca?1.941-2.033?Fe³⁺?0.596-1.000?Al?2.072-2.409?[Si?2.889-3.068?O11]O?OH?.The spectroscopic tests of epidote from Fushan include infrared spectroscopy and X-ray powder diffraction.The result shows that the main absorption peaks of infrared spectroscopy are located in 3700 cm^-1 to 3400 cm^-1,1200 cm^-1to 900^-11 and 800 cm^-to 400cm^-1.The epidote particles has strong diffraction peaks and other minerals are weak.That proved the secondary minerals in epidote crystals are less,which confirms the results of EPMA analysis.The characteristic spectral lines of epidote are 4.0190?200?,3.4882?011?,2.8617?002?2.9006?-113?,and 2.5321?202?.The fluid inclusions in epidote of Fushan are numerous and appear in groups.The distribution of fluid inclusions is lrregular.The type of fluid inclusions is mainly apperaed in gas-liquid two-phase fluid inclusions.Most of the inclusions are elliptical with small size and have clear boundarie.The homogenization temperature is mainly around 200?,the salinity of the inclusions is 19.05 to 23.71wt%NaCI,the average is 18.27wt%NaCI,the density range is around 0.92 to 1.04 g/cm ³ and the average pressure is 28.2 MPa.Combining with the scholars experience,test results and comparing the characteristics of epidotes of various characteristics,it is concluded that the epidote in this test is formed by direct crystallization in the hydrothermal solution which has been subjected by later period metamorphism.