DISTRIBUTION OF TRACE ELEMENTS IN SPODUMENE: INSIGHTS FROM PRELIMINARY P-XRF RESULTS
The TM pegmatite is an inclined, pipe-shaped body, 200 x 20 x 30 m in size that has been historically mined for spodumene and Cs in pollucite. The recently discovered PBN pegmatite is an irregularly-shaped, internally-zoned body, 300 x 600 m in surface exposure, that is being evaluated for Li ore potential (Simmons et al., 2019). Both pegmatites contain giant crystals of spodumene in their inner zones, ranging from dm’s to m’s in size, as well as pollucite, beryl, amblygonite, cassiterite, and columbite-group minerals.
We investigated the trace-element distribution along slabbed, crystallographically-oriented, subhedral spodumene collected from TM and PBN pegmatites. We used a Tracer 5i portable X-Ray Fluorescence unit to produce 2D compositional maps for trace elements including Mn, Fe, and Sn. Average Fe2O3 contents (wt%) are lower for PBN (0.22 ± 0.01 N=143) than for TM (0.59 ± 0.20 N=596). Through transmitted light and cathodoluminescence (CL) observations, we documented the effects of microscopic inclusions and fractures, which yielded chemical anomalies of apparent secondary nature. Using these techniques, we were also able to reveal the presence of chemical heterogeneities resembling growth zones, suggesting the existence of BL’s in large to giant spodumene crystals.