Mineralogy And Quality Evaluation Of The Shuangshan Jade Deposit In Fangcheng,Henan Province

With the continuous development of the national economy,people's demand for jade has been on the rise.However,due to the special natural characteristics and rarity of jadeite,Hetian Jade,Dushan Jade and other jade resources,added with the expanding application scope of jade,it became necessary that we develop other varieties of jade aside from these famous ones to satisfy the huge demand of the people for jade.Over the past few decades,along with the rapid growth of modern geology and gemology,scholars at home and abroad have done much work on the geological,mineralogical and classification identification standards of jade,the craftsmanship and other aspects,especially the research of jadeite,Hetian Jade,Dushan Jade and other widely-known jade varieties,which was found relatively detailed with a systematic quality evaluation standard.However,due to lacked understanding,limited circulation and other reasons,certain jade varieties lacked systematic and detailed research,for which there wasn't a unified quality evaluation standard for them,thus impeding the development of the jade market to a certain extent.Addressing this problem,in this paper,the author chose the Shuangshan Jade from Fangcheng County in Henan province as the main object of study and focused on the mineral composition and quality evaluation of Shuangshan Jade,from which the following results were achieved:1.On the basis of the detailed field survey,the author determined the basic rock associations and contact relations in Shuangshan Jade mining area in Fangcheng county;it was found through initial investigation that the ore body mainly occurred in the marble of Luanchuan Cluster Sanchuan Group and the dolomite-marble of Nanni Lake Group and the jade was dominated by grammatite,diopside,serpentine and aktinolith;the ore body was located near the contact strip outside the Neoproterozoic intrusive rocks,and was found in big xenoliths in some sections;with gradient transition from the marble in general.2.Combined with indoor lithofacies identification,analysis of characteristics of mineral components,X-ray diffraction analysis and the research of other aspects,the author inferred that the formation of Shuangshan Jade Ore was the result of hydrothermal alteration upon the contact of marble influenced by later magmatic intrusion near the magma contact strip,hydrothermal source being the later magma.It was concluded that the main mineral composition of Shuangshan Jade included grammatite,dolomite,calcite and serpentine,and the auxiliary minerals were mainly diopside,chlorite,etc.,with granoblastic structure primarily.3.The Shuangshan Jade within the area could be divided into five varieties by color: gray Shuangshan Jade,white Shuangshan Jade,yellow Shuangshan Jade,green Shuangshan Jade and streak Shuangshan Jade.The author further rated the color,gloss,transparency,texture,lumpiness and craft of the Shuangshan Jade respectively,and creatively established a collection of permutations and combinations of factors affecting the quality for the comprehensive evaluation of the quality of Shuangshan Jade.