Paper No. 184-11
Presentation Time: 2:30 PM-6:30 PM
RARE-EARTH ELEMENT OCCURRENCE IN HEAVY MINERAL SANDS IN SOUTHEAST GEORGIA
Rare-earth elements are currently mined domestically from Mountain Pass, CA and from heavy mineral sands in southeast Georgia. These heavy mineral sands have been developed for their reserves of titanium and zirconium minerals. A monazite, xenotime, and zircon sand concentrate (monazite sand) prepared from the Georgia heavy mineral sands featured a high concentration of rare-earth elements (REE). The total REE in this monazite sand is 60,189 ppm. This monazite sand concentrate is enriched in both the light rare-earth elements (Sc, La-Eu; LREE) and the heavy rare-earth elements (Y, Gd-Lu; HREE) relative to Upper Continental Crust (UCC). UCC-normalized La/Lu is about 0.03. The HREE are attributed to the presence of both xenotime and zircon. A slight positive Sc anomaly (2 - 3.5 times relative to UCC) was observed in rutile, ilmenite, and leucoxene. Mineral separates of zircon (Total REE = 1,531 ppm), rutile/anatase (Total REE = 130 ppm) and ilmenite (Total REE = 266 ppm) contained lower concentrations of the REE compared to those concentrations typically known for xenotime and monazite. Previous work indicates that the source of the southeast Georgia titanium and zirconium minerals is igneous and metamorphic rocks of the Piedmont and Blue Ridge, with no distinct signature indicating a precise provenance. The REE in the monazite, xenotime, and zircon apparently derive from these same rock terranes. The heavy mineral sands in Georgia represent significant resources in both the LREE and the HREE.