Quantitative Mapping of Germanium Distribution in Sphalerite: Integration of Raman Spectroscopy and LA-ICP-MS

Sphalerite (ZnS) is a major host mineral for numerous critical metals at minor or trace levels, including germanium (Ge), gallium (Ga), and indium (In). In situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is the standard technique for mapping trace elements, yet it causes sample damage and compromises measurement reproducibility. In contrast, Raman spectroscopy offers a minimally destructive, rapid alternative but has rarely been applied to quantify Ge in natural sphalerite. In this study, we present an integrated novel workflow combining Raman spectroscopy and LA-ICP-MS mapping to quantitatively characterize Ge distribution in sphalerite from the Nanmushu and Zhugongtang Zn-Pb deposits. Our results show that Ge incorporation into the sphalerite lattice induces consistent Raman spectral changes: a red shift of the 346 cm−1 peak and enhanced intensity of the 405 cm−1 peak. These variations become significant when Ge concentrations exceed 508 ppm, enabling clear identification of Ge-rich domains. Raman mapping and LA-ICP-MS mapping of spatially correlated domains yield highly consistent Ge distribution patterns. This integrated approach provides a rapid, non-destructive, and reliable means for quantitative microscale mapping of Ge in sphalerite, while preserving sample integrity. It resolves a long-standing challenge in microanalysis of critical metals in sulfide minerals and supports efficient characterization of Ge-enriched sphalerite in Zn-Pb deposits.