The Study On Gemological And Mineralogical Characteristics Of Fluorite In Zhuyuangou Deposit,Song County,Henan

The fluorites produced in the Zhuyuangou fluorite deposit in Song County,Henan Province have various colors.In order to study the causes of fluorite's color and the age of mineralization,this paper uses multiple methods of electron probe,ultraviolet-visible light absorption spectroscopy,infrared spectroscopy,Raman spectroscopy,fluorite Sm-Nd dating,and zircon U-Pb dating.The Zhuyuangou fluorite has undergone a systematic gemological test.Zhuyuangou fluorite is mostly produced by filling fissures in the form of veins.The ore-bearing surrounding rock is the biotite monzonitic granite of the Early Cretaceous,and the well-developed crystals are octahedral and cubic crystals.The colors of fluorite are mainly light green,light yellow,gray,light purple and purple,and the colors are mostly distributed in strips,usually translucent.The relative density of fluorite is 3.03?3.15,the Mohs hardness is 4,and the refractive index is 1.434(±0.01).It shows strong violet to blue-violet fluorescence under long-wave ultraviolet light,and weak violet to blue-white fluorescence under short-wave ultraviolet light.Phosphorescence.The chemical composition of Zhuyuangou fluorite is mainly composed of F and Ca,and contains trace elements Na,Mn,Fe,Ti,Ni,Si,Cr,K,Al.Raman spectroscopy shows that fluorite contains mineral inclusions such as barite,anatase,and quartz.Combined with infrared spectroscopy analysis,fluorite may also contain a large amount of CO₂ gas-liquid inclusions.The ultraviolet-visible light absorption spectra of different colors of fluorite have absorption bands with different intensities in the vicinity of 224nm?244nm,near 303nm,360nm?380nm,near 400nm,and 560nm?580nm.According to the attribution of the peaks,the cause of the color of fluorite include Rare earth elements,F color centers and composite F color centers,radioactive elements,colloidal calcium or colloidal calcium plus F color centers.In the infrared spectrum,there are 1080 characteristic peaks of fluorite and 665 CO₃^2-flexural vibration peaks in the fingerprint area.The functional group area contains 1436?1532CO₃^2-stretching vibration,2351 CO₂ characteristic peaks,2860?2926 organic groups and3430?3438 O-H The key stretches and vibrates.The results show that fluorite may contain water molecules.The Raman spectrum is characterized by the characteristic peak of fluorite at 320 and the characteristic peak of trivalent rare earth ion photoluminescence near 500?950 and 1100.The Sm-Nd isotopic age of fluorite is 126.8±9.1 Ma,indicating that the fluorite deposit was formed in the Early Cretaceous,close to the zircon U-Pb age of the Taishanmiao granite,the fluorite mineralization age and the early Taishanmiao magma activity.The time coincides,indicating that the genesis of the fluorite ore is related to the Taishanmiao pluton.The surrounding rocks of the mining fluorite mine resemble porphyritic syenite.The zircon U-Pb isotopic age of the surrounding rock is 140.12±0.34 Ma,which can be regarded as the crystallization age of the porphyritic syenite,indicating that it was invaded in the Early Cretaceous.