Study On The Characteristics Of Epigenetic Copper Minerals Of Quwu Silver-copper Deposit In Lanping County,Yunnan Province

The Quwu silver-copper deposit is located in Lanping County,Nujiang Prefecture,Yunnan Province.It is mainly located in the middle section of Tanggula-Changdu-Lanping-Simao fold system,which is sandwiched between the Jinsha River and Lancang River deep faults,and the northern direction of Lanping-Simao Cenozoic basin.The mineralization zone is about 4500m long and 20²00m wide.The overall mineralization in the area is continuous and mainly produces industrial ore.The ore minerals are mostly epigenetic copper minerals with various types and complex composition.In this paper,the epigenetic copper arsenate minerals in the Quwu area are the main research objects.Through modern analytical testing methods,including X-ray diffraction analysis,scanning electron microscopy,infrared characteristic spectroscopy,electron probe spectrum analysis,etc.The mineral characteristics of epigenetic minerals such as chlorite and hydroxyarsenite have been studied in detail and the following results have been achieved:1.The silver-bearing minerals in Quwu silver-copper mining area are mainly argentite,freibergite,followed by pyrite,arsenopyrite and other metal sulfides.The topogenic minerals are arsenate minerals,carbonate minerals,in which arsenate minerals are often tyrolite,olivenite group minerals,conichalcite group minerals,carbonate minerals are mainly azurite,malachite and so on.2.The mineral chemical composition of tyrolite in this area is complex,and the diffraction characteristics show that the periodic repeated arrangement in the direction of vertical structural layer is lost,and whether there are special structural properties caused by the simultaneous existence of carbonate and sulfuric acid,interlayer water and hydrogen bond or other reasons.And further study is needed.3.Olivenite group minerals include olivenite and adamite.The analysis of two kinds of mineral composition shows that Cu and Zn are isomorphism for each other to form continuous solid solution.Copper and zinc mainly exist in this two mineral forms in our silver-copper deposit.4.Other arsenate minerals are commonly composed of conichalcite and duftite,which are characterized by obvious growth zone phenomenon.The two minerals are symbiotic minerals,and the content of Pb changes significantly.5.In the region,the in-situ sulfide mineral in the copper deposit of the region is formed by continuous leaching oxidation,and metal cations such as Cu²⁺and Pb²⁺,which are active in the sulfate,can not only generate carbonate minerals in the reaction process with the medium such as the surrounding rock,it is also possible to react with an arsenic acid to form an arsenate mineral.The mineral of arsenate is a neutral-weakly basic?pH=6⁸?environment,and the sulfide minerals of the silver-copper deposit in the region are inferred to be the neutral-weak alkaline condition of the late-stage sulfide and the acidic medium in the oxidation stage in the late stage?epigenetic phase?.