Kegelite: Infrared Spectroscopy and a Structural Hypothesis

R. S. W. Braithwaite
Chemistry Department, University of Manchester Institute of Science and Technology, Manchester M60 1QD, England

Abstract: The infrared spectrum of kegelite has been measured and is discussed. The infrared spectra of 1 : 1 molar mixtures of leadhillite with pyrophyllite or with muscovite resemble the spectrum of kegelite, the chemical formula of which is a 1 : 1 stoichiometric sum of those of pyrophyllite and of the leadhillite polymorphs. Kegelite is not a physical mixture of these species, but its structure may be an interlayering of phyllosilicate and leadhillite-like structures within the unit cell. The unit cell parameters of pyrophyllite-1Tc and the leadhillite polymorphs are compatible with each other and can be combined to give a cell with parameters close to those of the kegelite cell. A structural model for kegelite on these bases is suggested, which is also consistent with its thermal analysis. The formula of kegelite can be written as Pb8(SO4)2(CO3)4(OH)4(AlOH)4(Si4O10)2.

Keywords: kegelite • infrared spectrum • pyrophyllite • leadhillite

Mineralogical Magazine; March 1991 v. 55; no. 378; p. 127-134; DOI: 10.1180/minmag.1991.055.378.11
© 1991, The Mineralogical Society
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