Application of In-situ Micro-XRF Spectrometry in the Identification of Copper Minerals

There are many types of copper minerals with different occurrences and complex compositions. The paragenesis and associated minerals make it difficult to traditionally identify the rock and mineral. In particular, the isomorphism of tetrahedrite and tennantite and the similar optical characteristics of copper minerals with pyrrhotine and cubanite make the identification of copper mineral difficult by Polarization Microscope or Reflection Microscope. In this paper, an account of how the copper mineral was scanned by X-ray Fluorescence Spectrometry (XRF) with microanalysis is given. By selecting the measurement conditions, measurement modes, and interference correction model (spectral overlap and matrix effects), the identification method was established. This method has excellent precision and accuracy. The relative standard deviations (RSD) of S, Fe and Cu are 0.74%, 0.86% and 0.18%, respectively for 12 repeated analyses of chalcopyrite. Single analysis of copper mineral standard yields the RSD less than 6%. The proposed method can identify tetrahedrite from Ag-As tetrahedrite, and also pyrrhotite and cubanite. This method is effective and can provide two-dimensional or three-dimensional images of the major elements and associated elements, which directly show the distribution of minerals and provides valuable information for accurately naming copper minerals and the comprehensive utilization of minerals.