OCCURRENCE OF THE LANTHANIDE RARE EARTH ELEMENTS IN THE GEORGIA KAOLINS AND HEAVY MINERAL SANDS

Rare earth elements (REE) consist of the Lanthanide Series of Rare Earth Elements, La-Lu, Y, and Sc. REE are used in the manufacture of technological products, including computers, batteries, lasers, magnets, metal alloys, and MRI contrast dyes. China provides more than 97% of the world’s REE (Weng et al., 2015). Increasing technological advances in the US result in increased demands for REE; it would be in the US’s economic interest to have a reliable local source of REE. The presence of mineable sources of REE within the US would reduce the dependence on international sources of REE.

Recent research shows the heavy mineral subfraction of the coarse (grit, >44 μm) fraction of the Jeffersonville (JV) member of the Huber Formation and Buffalo Creek (BC) formation of Georgia kaolin deposits contain significant concentrations of the heavy rare earth elements (HREE, Gd-Lu, 1200-2500 ppm, Gardner, 2016); processed heavy mineral sand deposits of the Georgia coastal plain show high HREE concentrations (236-213,000 ppm). When normalized to Upper Continental Crust (UCC) values (Rudnick and Gao, 2003), the HREE show the highest enrichments relative to UCC (50-140 times for BC samples; 850-3381 times for heavy mineral sand samples). These concentrations comprise potentially mineable reserves of REE (Foley and Ayuso, 2015). Gardner’s (2016) work shows that zircon hosts the REE in the BC and JV heavy fractions; further study is being conducted on the REE host/s in the heavy mineral sands deposits. U-Pb dating of zircons from BC grit shows ages ranging from 311 MA to 1039 MA, suggesting parent rocks likely of Appalachian or intrusive late Paleozoic plutonic origin (e.g. Sparta granite). Currently, kaolin ore coarse fractions are discarded and used as backfill in the mined kaolin quarries. REE could potentially be co-produced alongside the processing of raw kaolin ore and heavy mineral sands ore, resulting in a reduced dependence on international sources of REE. This study has two hypotheses: determination of 1) the minerals hosting REE in the heavy mineral fractions of mined kaolin and heavy mineral sands units of Georgia; and 2) the provenance of the minerals hosting the REE in each ore.