Secondary Minerals and Their Weathering Mechanisms of the Waste Sulfide-bearing Ores in Shizishan Mine,Tongling

An investigation on the waste sulfide-bearing ores in Shizishan Mine,Tongling,Anhui Province was carried out.By employment of XRD and SEM/EDS analyses,the mineral association of the weathered sample was disclosed and then the formation mechanism of secondary minerals was discussed.The major residual primal mineral identified is pyrite,and the secondary minerals are goethite,hematite,ferrihydrite and efflorescent sulfates.Pyrite firstly was oxidized from the flaw spot such as fissure,and then gradually oxidized until forming finally goethite.In the intermediate process,there are multiplicity of the secondary minerals and their morphology.Before goethite formed,the intermediary ferrihydrite might have been produced.Due to its unstable property,ferrihydrite would transform into goethite or hematite quickly under different conditions.There were various configurations of goethite.The acerose goethite was formed first and then recrystallized into globose and rhombic dipyramid goethite.In the end,the layer of dusty goethite formed on the waste ore's surface.SEM observation shows that there maybe biominerals in pyrite surface and hypha in the surface of the mostouter oxidized layer,which indicate that the organism might have been played a certain role in the weathering process of waste ores.