113 Mineralogical Characterization of Economic Resources: From Critical Minerals to Gemstones (Posters)

From ore materials to precious gemstones, minerals play an important role in almost every aspect of our lives. This session will focus on characterization of economic minerals employing spectroscopic techniques, geochemical analysis, and microanalytical techniques.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Critical Mineral Occurrences in kaolin-clays, Eufaula, Alabama

Paper number: 113-22
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Upper Coastal Plain Kaolins and bauxites contain a promising new inventory of REEs (Sc, Y, La-Lu). Core (28 feet total length, 52 feet to 80 feet below surface) was drilled into kaolin claystone within the Eufaula bauxite-kaolin mining district. This core was divided into 14 sub-samples, each representing a composite 2-foot sample. These subsamples were each separated into coarse (>45 µm) and fine fractions (<45 µm).  The coarse fraction was later separated into a heavy mineral fraction (>2.85 g/cm3) and a light fraction (<2.85 g/cm3). Heavy mineral fractions were also separated from the settled fine fraction (<45 µm). Kaolinite is the predominant mineral (75-97% throughout the core). Small amounts of quartz or gibbsite were present (<1%) based on X-ray diffractometry. The heavy rare-earth elements (Gd-Lu, Y; HREEs) are enriched 1.25 – 3 times relative to Upper Continental crust (UCC) in the bulk kaolin. The bulk kaolin was enriched in the LREE (La-Eu) at 73 ft depth. Total REEs ranged from 100 ppm – 500 ppm. Ga was 25 to 55 ppm.  Titanium was present mainly in the form of anatase, (~1 wt % throughout). Zr was 400 to 550 ppm, enriched by 2 – 3 times greater than UCC. Fe (III) steadily increased downward, reaching 26 wt. % at 80 ft depth. These data provide the basis for ion-extraction experiments and comparison to other kaolin ores in the Coastal Plain.  The goal is to improve our understanding of the source(s) and speciation of the rare earth elements in the Georgia-Alabama Upper Coastal Plain.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414764

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