Crystal dislocations and incorporation of Sc in hydrothermally modified beryl from LCT type pegmatites

Pegmatites of the lithium-cesium-tantalum type are widely dismissed as potential scandium hosts. Here we show that beryl from the Bailongshan pegmatite deposit in northwest China contains anomalously high scandium, with scandium oxide reaching up to 1.85 wt%, and present direct nanoscale evidence of dislocation-mediated critical metal enrichment in beryl. Scandium-rich beryl-bearing pegmatites form a distinct metallogenic subunit hosted in scandium-rich two-mica schists. Beryl crystals have a magmatic core surrounded by a hydrothermal rim; despite continuous crystal structure, the rim holds nearly twice the scandium content of the adjacent dislocation-free core. Dislocation arrays in the rim create fast-diffusion pathways and expand atomic sites to accommodate scandium leached from wall rocks by hydrothermal fluids, with whole-rock grades corresponding to an estimated 7.4–12.0 kiloton scandium resource. This post-crystallization, dislocation-driven mechanism operates independently of magmatic fractionation, redefining such pegmatites intruding scandium-rich metasedimentary rocks as underexplored global scandium resources. Hydrothermal alteration generated dislocations in beryl rims that facilitated Sc diffusion and enrichment, leading to significant scandium accumulation and highlighting the Bailongshan deposit in Northwest China as a promising Sc resource, according to geochemical and crystallographic analysis.