Trace element composition and molecular-scale speciation characterization of sphalerite from Central and East Tennessee mining districts, Red Dog mining district (AK), and Metaline mining district (WA)

Germanium (Ge) is an element deemed critical globally, and used in electronics, communication, and defense applications. The supply of Ge is limited and as demand for it increases, its criticality increases. Germanium is exclusively recovered as a byproduct of either coal mining or zinc (Zn) mining, and the main mineral hosting Ge in Zn deposits is sphalerite (ZnS). However, the mechanisms of Ge enrichment in sphalerite during mineral deposit formation are poorly understood. Therefore, investigations on the mechanisms controlling geologic enrichment of Ge in ores is crucial for maintaining a sustainable supply.

For this study, we used a combination of techniques including optical and electron microscopy, synchrotron-based x-ray absorption spectroscopy (XAS, bulk and micrometer-scale), x-ray diffraction (micrometer-scale), and x-ray fluorescence (micrometer-scale) mapping, and cathodoluminescence to characterize Ge and co-substituent trace elements in sphalerite from four mining districts where Ge is, or has been, recovered in the United States: Central and East Tennessee, Red Dog (AK), and Metaline (WA). Here we present the numerical component of this dataset which includes (1) the concentration of trace elements from electron microprobe analysis and (2) the results of linear combination fits from x-ray absorption near edge spectroscopy (XANES) analysis of Ge to estimate the amounts of Ge2+ and Ge4+, and of Cu to estimate amounts of various types of bonding environments. This work is being conducted in tandem with a complimentary study that explores the environmental behavior of Ge, and the potential to recover Ge from mine wastes at the Tar Creek Superfund site in Oklahoma, USA (White and others, 2022a and b).