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GEOREF RECORD

Thermal reactions of leadhillite; Pb (sub 4) SO (sub 4) (CO (sub 3) ) (sub 2) (OH) (sub 2)

A. E. Milodowski and D. J. Morgan
Thermal reactions of leadhillite; Pb (sub 4) SO (sub 4) (CO (sub 3) ) (sub 2) (OH) (sub 2)
Clay Minerals (December 1984) 19 (5): 825-841

Abstract

Reactions undergone by leadhillite from the type locality on heating to 1000 degrees C have been followed by DTA, TG, DSC, evolved gas analysis, continuous-heating XRD and IR, and hot-stage microscopy. Intermediate decomposition products were identified by X-ray powder photography. At 80 degrees C, biaxial leadhillite inverts to a uniaxial phase with properties similar to those of susannite, a naturally occurring polymorph of leadhillite, but this higher-temperature modification only partially reverts to the original structure on cooling (up to 24 hours at room temperature is required for complete reversion). Between 250 and 600 degrees C the mineral undergoes two decomposition reactions: PbO.PbCO (sub 3) and PbO.PbSO (sub 4) form during the first reaction (PbCO (sub 3) may form in the initial stages) and 4PbO.PbSO (sub 4) during the second. alpha -2PbO.PbSO (sub 4) appears at 650 degrees C due to solid-state reaction between the other lead oxysulphate products. Melting occurs above 850 degrees C. The reaction products are discussed in relation to the phase diagrams for the systems PbO-CO (sub 2) and PbO-PbSO (sub 4) .


ISSN: 0009-8558
Coden: CLMIAF
Serial Title: Clay Minerals
Serial Volume: 19
Serial Issue: 5
Title: Thermal reactions of leadhillite; Pb (sub 4) SO (sub 4) (CO (sub 3) ) (sub 2) (OH) (sub 2)
Affiliation: Br. Geol. Surv., Geochem. Dir., Keyworth, United Kingdom
Pages: 825-841
Published: 198412
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 24
Accession Number: 1985-053191
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Update Code: 1985
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