Ti-Bearing Phases in the Huber Formation, an East Georgia Kaolin Deposit

Abstract

Abstract--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 2 content in the bulk fraction ranges from 1.2 to 5.4 wt. %. There are at least three Ti-bearing phases, including anatase, ruffle, 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 ruffle occurs in trace amounts. Bulk XRD analysis correlates well with the bulk TiO2 chemical measurements. Average anatase unit-cell parameters are a = 0.37908 -+ 0.0002 nm and c = 0.951 +_ 0.001 nm. These parameters indicate an approximate chemical formula of Fe3+0.05Ti4+0.95Oi.95(OH)0.05.The distribution of TiO2 content as a function of depth may be useful to obtain original grain-slze 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 Hnber Formation are consistent with a previously published theory for kaolin genesis that includes biomineralization of originally coarser-grained aluminosilieates into a kaolinite-rich ore body.

Mineralogy and Physico-Chemical Data of Two Newly Discovered Halloysite in China and Their Contrasts with Some Typical Minerals

“…The main impurity in halloysite was Fe 3+ (which existed as hematite or maghemite, and even partly substitute positions of Al 3+ in the octahedral sheet [15,43]), Ca 2+ and K + (which often coordinates with oxygen atoms on the edge of the polyhedrons to compensate the excessive electronic charges, these cations may be exchangeable, or existed in the form of carbonates that cannot contribute to the cation exchange). The Hal-AU, Hal-SY and Hal-TL had a trace amount of Ti content, indicative of the anatase (TiO 2 ) impurity [44]. P 2 O 5 and SO 3 were detected because of the existence of the aforementioned excessive cations in forms of phosphates and sulphates.…”

Alteration of Volcanic Rocks and Genesis of Kaolin Deposits in the Şile Region, Northern Istanbul, Turkey. I: Clay mineralogy

“…Kaolinites, from the core samples have higher calculated tetrahedral Al contents than ideal kaolinite contents (Table 2). Most Fe 2 O 3 and TiO 2 are attributed to oxides because the presence of free very fine-grained Fe oxide and anatase in sediment-hosted kaolins is very common (Weaver, 1976;Schroeder and Shiflet, 2000). Also, the SiO 2 contents of sample 99/659 in Table 2 and XRD data indicate the presence of claysize quartz.…”

Mineral-Aqueous Solution Interfaces and Their Impact on the Environment

“…A visual difference in the nature of the Fe-nanophases associated with clays is the yellowing of kaolins during deferration treatments, indicating the preferential dissolution of nano-haematite coatings . Similarly, nano-Ti-oxide coatings often occur on kaolins, nano-anatase being the dominant phase (Malengreau et al ., 1995;Schroeder and Shiflet, 2000) (Fig . 14 .12) .…”