Gemmological and Spectroscopic Characteristics of the Emerald from Musakashi, Zambia

Compared with Kafubu emeralds from Zambia, emeralds from Musakashi possess unique gemmological characteristics. This study selects 14 emeralds from the Musakashi mine as subjects, examining their characteristics using conventional gemmological instruments, laser Raman spectrometer, infrared spectrometer, microscopic UV-Vis-NIR spectrometer, and laser ablation inductively coupled plasma mass spectrometry. Results indicate that the average relative density of the emerald samples from Musakashi, Zambia is 2.65. They exhibit red fluorescence under long-wave ultraviolet light, but inert under short-wave ultraviolet. The samples are relatively clean inside, featuring elongated growth tubes arranged in parallel, beryl and "lotus root" inclusions. The fluid inclusions are mainly multi-phase, presenting jagged, elongated, and rectangle shapes. The gas components include CO₂ and N₂, the liquid phase is consisted of H₂O, and the daughter minerals including halite and a carbonate.Infrared spectra revealed that the water molecules within the emerald channels are primarily Type Ⅰ water, showing prominent absorption peaks at 7 144, 6 819 cm^-1 and 5 105 cm^-1 in the near-infrared spectrum. UV-Vis-NIR absorption spectra demonstrated that the colour of the emerald samples is predominantly influenced by Cr³⁺ ions. LA-ICP-MS analysis indicated that the Musakashi emeralds are characterized by low concentration of Fe, Mg, and alkali element, coupled with high Cr and V content. Binary log-log plots of Li versus K and Rb versus Cs content can distinguish the Musakashi mine from other significant emerald deposits worldwide.