| This study used conventional gemological test methods,combined with modern testing methods,to observe,test and analysis the morphology,conventional gemological characteristics,trapiche pattern features,inclusion characteristics,chemical composition and spectral characteristics of the trapiche quartz in the Huanggangliang area of Keshiketengqi,Chifeng City,and the Dongwuqi area of Xilin Gol League,Inner Mongolia.Adopting the theory of crystal growth and the typomorphic mineral characteristics to disscuss the formation conditions of the crystals and the origin of the trapiche phenomenon.The trapiche quartz in the Huanggangliang area is a short columnar euhedral crystal,and there is a "black core" when the crystals are backlit.The arms of the trapiche phenomenon are formed by six radial dark color bands located along a-axis of the crystal while the core of the trapiche pattern is a hexagonal color-zoning,.This trapiche pattern is resulted from the exact special spatial distribution of the color-inducing elements.These samples belong to the group of trapiche-like gems.The trapiche-like quartz found in the Huanggangliang area in this study is the first time that the trapiche phenomenon discovered in smoky quartz and also the first time that the crystal formed the trapiche pattern only by the color-zoning itself.The trapiche quartz found in the Huanggangliang area contains a large number of green fibrous inclusions,yellow semi-metallic lustrous spheroidal inclusions,and fluid inclusions.According to the position and the interpenetration relationship between the inclusions and quartz,supposed that the fibrous inclusions and the spherical inclusions are protogenetic inclusions.EPMA and Raman spectroscopy showed that the green fibrous inclusions were ferroactinolite.According to the morphology,composition and CL characteristics of Huanggangliang trapiche quartz,it is supposed to be the pegmatite genesis.The trapiche quartz found in the Dongwuqi area is columnar and formed by a large number of double-cone quartz crystals.Its trapiche pattern is formed by the alternative distribution of the inclusions and therefore belongs to trapiche-like gemsgroup.The six fixed star lines of the trapiche pattern are along the a-axis.A large number of "fibrous" inclusions located in the triangular area separated by the six star lines,made these areas opaque,forming the trapiche pattern.Oriented "fibrous" inclusions found to be numerous intermittent elongated irregular-shape inclusions arranged in one direction under magnification.The elongated direction of the "fibrous" inclusions is corresponding to the crystal growth direction when observed under the crossed-polarizing microscope.It is speculated that the orientation of the "fibrous" inclusions may be related to the crystal growth process such as complicated "parallel growing" or twin.In addition,microscopic observation also found that Inner Mongolia Dongwuqi trapiche quartz contains fluid inclusions,non-directional fibrous inclusions and other crystal inclusions.The SEM image shows that the cross-section of the "fibrous" inclusions in the trapiche quartz of Dongwuqi appears as dense circular or irregular holes.Raman spectroscopy found that the crystal contains mineral inclusions such as hematite and pyrochlore.However,the Raman spectroscope did not find out the phase of the inclusions causing the trapiche phenomenon.Combined with the irregular shape of such inclusions observed under the microscope,it is speculated that these inclusions may be some debris of surrounding rock and are protogenetic inclusions. |
