Berry-Shaped, Vivid Green Grossular Within Green Nephrite from the Polar Deposit in Canada

Green nephrite of the serpentine-replacement type often consists predominantly of the actinolite–tremolite series, with minor minerals such as uvarovite, grossular, chromite, magnetite, diopside, zircon, apatite, epidote, graphite, and phlogopite, which commonly reduce gem quality. However, nephrite from the Polar deposit in Canada represents an exception. This material consists mainly of the actinolite–tremolite series, with minor Cr-bearing grossular garnet and chromite. Actinolite–tremolite occurs as aggregates of fine fibers without obvious orientations, surrounding centimeter-scale, vivid green, berry-shaped garnet aggregates, within which residual chromite islands were observed. This vivid green color occurs over extensive areas, enhancing rather than reducing gem quality. Garnets contain 0.53–0.90 Cr apfu with lower Fe content, whereas amphiboles exhibit 0.01–0.06 Cr apfu and 0.46–0.87 Fe2+ apfu, values significantly higher than that observed in the adjacent grossular. Garnet is a minor mineral occasionally existing in green nephrite; however, the discovery of berry-shaped, vivid green garnet has only been reported at this location. The fine-grained, Al-rich garnet aggregates with relatively low Cr and Fe content suggest that a continuous replacement reaction potentially occurred. A more multifaceted value assessment framework that emphasizes the uniqueness of artistic expression and cultural connotation are proposed.