Gemmological Characteristic and Identification of a Type of Viridis Nephrite

The spectral characteristics and mineral components of a type of emerald-green nephrite available on the market were investigated, using testing methods such as infrared spectroscopy, Raman spectroscopy, UV-Vis-NIR spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, and laser ablation inductively coupled plasma mass spectrometry. The infrared and Raman spectroscopy of the main part of the samples showed the primary mineral component was tremolite. Energy-dispersive spectroscopy results showed that the main components of the sample are approximately 59.31% SiO₂, 25.10% MgO, and 12.62% CaO, which are generally consistent with the standard mass fractions of tremolite.The UV-Vis-NIR spectra of the sample exhibited absorption bands around 280, 460, 660 nm and 695 nm and the last three absorption bands were presumed to be related to Cr³⁺. LA-ICP-MS test results further revealed trace amounts of chromium in the sample, with concentrations ranging from 554.0 μg/g to 620.0 μg/g. Based on the above characteristics and in accordance with the national standard GB/T 38821-2020 Hetian Yu—Testing and Classification, the samples are identified as nephrite (viridis nephrite).