Backscattered electron images and chemical maps (b) of Nb-Ta oxide minerals from FA Li-pegmatites. (a) Columbite-group minerals (CGM) in association with albite and amblygonite-group minerals (AGM) in the Ramalha petalite-rich pegmatite (P016). Note relics of K-feldspar in albite. (b-d) Variably zoned CGM crystals from (b-c) the Bajoca petalite-rich pegmatite and (d) P010 Li-mica-rich pegmatite. Note rims or mantles with light BSE signals reflecting high Ta/Nb ratios. (e) Fluorcalciomicrolite from the Ramalha-West (P017) Li-mica-rich pegmatite.