Structure Characteristics of Dickites in Copper-Gold Deposit

Dickite as a type of clay mineral that is utilized in industries such as papers,ceramics,paints,cosmetics and fillers is widely distributed in Zijinshan(ZJS) Au-Cu deposit in southeastern China.In this paper,three types of dickites(i.e.,transparent,translucent and opaque),which were selected by optical microscopy,were investigated by X-ray diffraction(XRD)-Rietveld method based on the EVA and TOPAS softwares.The results show that transparent dickite is lowly ordered and poorly crystallized.Compared to other two dickites,the transparent one has a lower value of DC index and thinner average flake thickness along c-axis.Furthermore,the crystal structure of transparent dickite has a greater number of distortions of[SiO]tetrahedron and[AlO]octahedron,compared to that of translucent and opaquedickites.The results by the XRD-Rietveld method were confirmed by field emission scanning electron microscopy(FESEM) and electron probe micro-analysis(EPMA).Therefore,transparent dickite with low degree of order and irregular particle shape is not suitable for use in ceramic industry.