Phosphate minerals with rare elements in kaolins

Geochemical investigations of the primary and secondary kaolins from the Lower Silesian deposits yielded the unusually high contents of Pb, Sr and Ba as compared with the other trace elements. Concentrations of Pb, Sr and Ba sometimes reach values over 1000 g/t. Maximum contents of those elements in...

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Bibliographic Details
Main Authors: Szpila Kazimierz
Dzierzanowski Piotr
Corporate Author: International Kaolin Symposium (10.) (1979) (Budapest)
Format: Article
Published: University of Szeged, Department of Mineralogy, Geochemistry and Petrology Szeged 1980
Series:Acta mineralogica-petrographica 24
Kulcsszavak:Kőzettan, Ásványtan, Földtan
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Online Access:http://acta.bibl.u-szeged.hu/24677
Description
Summary:Geochemical investigations of the primary and secondary kaolins from the Lower Silesian deposits yielded the unusually high contents of Pb, Sr and Ba as compared with the other trace elements. Concentrations of Pb, Sr and Ba sometimes reach values over 1000 g/t. Maximum contents of those elements in the secondary kaolin from the deposit Maria III were found in the grain class <2/zm, whereas in the primary kaolins developed both from the Strzegomand Strzelin granitoids often two different grain classes of each sample of kaolin bear high concentrations of Pb, Sr and Ba. An attempt was made to determine the mode of occurrence of those elements, using the transmission electron microscopy and electron microprobe method. Single grain preparations and their replicas obtained by the controlled etching of kaolins with hydrofluoric acid were applied for electron microscopy. In addition to the main minerals easily dissolving in HF (kaolinite, quartz, micas) and accessory ones resistant to the etching (anatase, rutile), the third kind of grains was found, being etched only in part. The latter were analysed by electron microprobe method. The obtained spectra bear intensive excited X-ray radiation with wavelengths typical of Al, Pb, Sr and P, and moreover, sometimes weaker radiation of Ce, La, Ba and Ca. Analysis of the chemical composition and characteristic morphological features of the studied grains proved that in the fine grain classes of kaolins commonly there occur minerals from the groups goyazite SrAl3[(P04)2(0H)5]. HaO and plumbogummite PbAI3[(P04)2(0H)5] HaO. Chemical composition of the individual grains of the discussed mineral groups, all derived from the same kaolin specimen, suggests that strontium and lead may replace diadochically one another, resulting in the series of solid solutions, with a participation of phosphate molecules bearing La, Ce, Ba and Ca.
Physical Description:101-110
ISSN:0365-8066