Kinetic controls on Sc distribution in diopside and geochemical behavior of Sc in magmatic systems

Scandium is important in modern technology and regarded as a strategic metal many countries. It highly dispersed Earth’s crust rarely forms independent minerals. Clinopyroxene the most Sc-bearing mineral some world-class deposits hosted mafic–ultramafic intrusions, which are also major source of laterite-hosted Sc deposits. However, factors controlling distribution minerals have been little explored, impeding understanding geochemical behavior why it common clinopyroxene grains. The newly discovered Mouding deposit SW China zoned intrusion composed, from core to rim, monzogabbro, syenogabbro, gabbro, magnetite clinopyroxenite, clinopyroxenite. diopsidic composition with high contents (80–105 ppm). In-situ trace element mappings diopside crystals reveal homogeneous, zoned, swallow-tailed, hourglass internal patterns. These patterns can be produced through kinetically controlled incorporation on different crystal faces. preferential substitution take place {1 0 0}, 1 0} {0 prism faces because flexibility octahedral M1 protosites. fast growth diopside, facilitates crystallization, dominated by textural coarsening promoted hydrous parental magmas low viscosities active convection. flow efficient interstitial communication magma direct compatible elements into clinopyroxene, thus favoring formation Sc-rich Our study provides feasible way intra-grain variations emphasizes that kinetic effects may play critical role enrichment magmatic We show disequilibrium crystallization more pervasive than previously thought, zoning provide valuable information this process.