Beryl Mineralogy and Fluid Inclusion Constraints on the Be Enrichment in the Dakalasu No.1 Pegmatite, Altai, NW China

The Dakalasu No.1 pegmatitic rare-element deposit is a representative of Be-Nb-Ta pegmatites in Altai, Xinjiang, China. Beryl the most important beryllium-carrying mineral pegmatite. To constrain concentration mechanism Be, we conducted study textural relationships and chemical compositions (major trace elements) beryl, along with microthermometry Raman spectroscopy on beryl-hosted fluid inclusions. Two generations beryl were recognized. early I was formed magmatic stage, whereas late IIa IIb magmatic-hydrothermal stage. Lithium Cs contents increased from I, IIa, to IIb, Mg Rb decreased. Scandium, V, Ga are similar but different I. Titanium enriched IIa. high FeO Na/Cs ratios (I, IIb) reveal low degree differentiation evolution types melt inclusions four identified associated quartz. results indicated that II at 500 °C–700 °C, 200 MPa–300 MPa. pegmatite volatiles, such as B, F, CO2, evidenced by large amount tourmaline wall zone, occurrence variety tiny cryolite (Na3AlF6) inclusions, CO2-rich enrichment Be may be related crystallization highly undercooled states melt, melt–melt–fluid immiscibility during melt.