Characteristics And Genesis Of Jadeite In Qingshuihe Area,Qinghai Province

Based on the previous studies,regional geology and mineralization researches,this paper focuses on the distribution of ore-host deposit and effecting factors of the jade deposits in the area.The research results are as follows: 1)made a detailed description of the basic characteristics of the jade deposits.The Xiuyan jade developed in the area which are determined to serpentine jade,which has a fiber-morphized and blocked structure.It is mainly composed of serpentines,being waxy-glossy,translucent,with fine texture,low hardness,small blockiness and toughness,and the color easily changed,and more developed cracks.Color,structure,mineral composition,transparency,gloss and Mohs hardness,texture,toughness,blockiness were the main factors affecting the grade of jade;2)determined the geological background and ore-controlling conditions of jade output.The jade deposits in the area was a product of the hydrothermal metamorphism between the magnesium-rich carbonate rocks and the Indosinian intermediate-acid intrusive rocks,belonging to the typical contact metasomatism metamorphic deposits;3)made a systematic summary of the output characteristics and metallogenic regularity of the jade ore bodies.The ore body output was controlled by strata,intrusive rocks and structures,of which the ore-bearing strata was the main factors for ore controlling,while fault structures did not play a leading role in the formation of ore bodies.The contact metasomatism between dolomite marbles and rock bodies was the main mineral source for the formation of jade ore in this area.The surrounding rocks of the jade mineralized bodies found in the area were mostly dolomitic marbles.The ore bodies were distributed near the medium-acid granodiorites and were mostly found on one side of or near the outer contact zone.In short,the marble segments of the paleoproterozoic Jinshuikou rock group was a favorable layer for the formation of Xiuyan jade.The contact segments between the medium-acid intrusive rocks and the magnesia-rich carbonate rocks were the best areas for mineralization.In this paper,the mineralization characteristics and metallogenic regularity of Qingshuihe jade deposits was provided,we hope to gain insight into exploration and development of jade ore within the area and in similar areas.