<p>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.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

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

  • Tao Hong,
  • Zhang Zhang,
  • Hai-Yang Xian,
  • Mei-Fu Zhou,
  • Ming-Guo Zhai,
  • Gao-Bin Chu,
  • Shang-Xian Su,
  • Qiang-Tai Huang,
  • Hong-Tao Shen

摘要

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.