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Ti-bearing phases in the Huber Formation, an East Georgia kaolin deposit

Paul A. Schroeder and Jason Shiflet
Ti-bearing phases in the Huber Formation, an East Georgia kaolin deposit
Clays and Clay Minerals (April 2000) 48 (2): 151-158


Six kaolin samples from the Lower Tertiary Huber Formation near Wrens, Georgia were analyzed using transmission electron microscopy (TEM), electron diffraction (ED), powder X-ray diffraction (XRD), chemical analysis, and magnetic susceptibility to characterize the Ti-bearing phases. Selected samples were treated with 5 M NaOH to remove kaolinite and concentrate the Ti-bearing phases for additional analysis. TiO (sub 2) content in the bulk fraction ranges from 1.2 to 5.4 wt. %. There are at least three Ti-bearing phases, including anatase, rutile, and a poorly defined nanocrystalline form. Anatase is most abundant and is commonly found with {010} faces in association with kaolinite edge and basal faces. The nanocrystalline form occurs at 0-1 wt. %, and rutile occurs in trace amounts. Bulk XRD analysis correlates well with the bulk TiO (sub 2) chemical measurements. Average anatase unit-cell parameters are a = 0.37908 + or - 0.0002 nm and c = 0.951 + or - 0.001 nm. These parameters indicate an approximate chemical formula of Fe (super 3+) (sub 0.05) Ti (super 4+) (sub 0.95) O (sub 1.95) (OH) (sub 0.05) . The distribution of TiO (sub 2) content as a function of depth may be useful to obtain original grain-size variations associated with relative sea-level changes responsible for the deposition of the Huber Formation. Evidence for original depositional sediment properties can be seen in the occurrence of pseudomorphic replacement of micas and fecal pellets by kaolinite. Additional evidence for post-depositional changes includes the sub-micrometer euhedral character and low Fe content of the anatase (relative to soil-derived anatase). These observations for the Huber Formation are consistent with a previously published theory for kaolin genesis that includes biomineralization of originally coarser-grained aluminosilicates into a kaolinite-rich ore body.

ISSN: 0009-8604
Serial Title: Clays and Clay Minerals
Serial Volume: 48
Serial Issue: 2
Title: Ti-bearing phases in the Huber Formation, an East Georgia kaolin deposit
Affiliation: University of Georgia, Department of Geology, Athens, GA, United States
Pages: 151-158
Published: 200004
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 27
Accession Number: 2000-042084
Categories: Geochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N32°45'00" - N33°19'00", W82°40'00" - W82°15'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Update Code: 200014
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