Mineralogical Characteristics Of Green Hair Quartz Produced In Huanggang Liang Mining Area, Inner Mongolia

On the basis of field survey and investigation,the mineralogical characteristics and color genesis of Inner Mongolia green hair quartz are systematically studied by means of large-scale instruments such as conventional gemological instruments,optical microscopes,X-ray powder diffractometers and electron probes,and the reasons for the forming reason of the green hair quartz is initially explored.The green hair quartz produced by the Huanggangliang tin-iron polymetallic deposit in Chifeng City,Inner Mongolia is rich in color,mainly dark green,gray-green,light green,dark green,smoke green and smoke color.It grows mostly in the form of crystal clusters,and the single crystal develops hexagonal prism and rhombohedral crystal surface.The transparency is generally poor,and most green crystals render glass luster.The green hair quartz has a refractive index of 1.54 and a relative density of 2.630-2.665.It is mainly symbiotic with calcite and ferroactinolite,and the accompanying minerals are andradite,ferristilpnomelane and the like.According to the color difference,the green hair quartz is divided into green series and smoke color series,in which the green series is mainly composed of green and other colors,and the smoke color series is mainly composed of green color.In the green hair quartz of different colors,acicular ferroactinolite inclusions are found,and the inclusions are concentrated in the near-outer regions of the crystal.The crystal shape,size and crystal concentration of the ferroactinolite mainly affect the color and transparency of the green hair quartz.The denser the fluid inclusions in the near-outer regions is,the more gray the color of the crystal is,and the lower the transparency is.In addition,the high content of Fe ions in the quartz substrate will make the crystal yellow.The content of Al³⁺is high,which will cause the crystal to be grayish due to the color of the hole color center generated by the substitution of Si⁴⁺.Therefore,the color of the green hair quartz is mutually affected by the ferroactinolite inclusions,the fluid inclusions and impurity ions.The fluid inclusion in the green hair quartz is a liquid-rich aqueous solution inclusion in the NaCl-H₂O type,with a uniform temperature of 256°C-350°C,a salinity w?NaCleq?of0.18%-23.18%,and a density of 0.65-0.99g/cm³.The inclusion is a medium-high temperature,medium-low salinity ore-forming fluid in overall.The inclusion is mainly formed in the late stage of complex skarn mineralization of skarn mineralization,early stage of quartz sulphide mineralization and its transitional stage,and it is mostly produced in quartz veins or crystal cavities distributed along the fracture in the form of crystal clusters.The ore-forming environment of crystal is unstable.During the growth process,it may undergo multiple stages of hydrothermal participation in mineralization,resulting in green hair quartz with different crystal surface patterns and color types.The green hair quartz are symbiotic or accompanied with minerals in many different mineralization stages.