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The nature and paragenesis of natural bredigite and associated minerals from Carneal and Scawt Hill, Co. Antrim

Published online by Cambridge University Press:  05 July 2018

P. A. Sabine ,
M. T. Styles  and
B. R. Young
P. A. Sabine
Affiliation:
British Geological Survey, Exhibition Road, South Kensington, London SW7 2DE
M. T. Styles
Affiliation:
British Geological Survey, Exhibition Road, South Kensington, London SW7 2DE
B. R. Young
Affiliation:
British Geological Survey, Exhibition Road, South Kensington, London SW7 2DE
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Abstract

Bredigite is a constituent of the very high-temperature, low-pressure, exomorphic suite of Carneal, Co. Antrim. Although this mineral is very rare in nature, it is an important constituent of some slags and cement clinkers but there has been much controversy about its nature, most of the evidence having come from artificial materials. Chemical analysis of the Carneal mineral shows it to be remarkably similar to that from the type locality, Scawt Hill (also analysed here), and that it is an individual mineral species of generalized ionic composition (Ca,Na)14(Mg,Fe2+Fe3+Mn)2(Si,P)8O32. Ba (abundant in the original analysis of the slag mineral) is not a constituent. Accurate X-ray powder data of the natural mineral are given. Bredigite is not Ca2SiO4, nor is it part of a solid solution of variable composition between larnite and merwinite. Analyses are presented for the associated minerals larnite (allowing appraisal of its composition), spurrite, and spinels. The paragenesis is discussed.

Keywords

bredigitelarnitespurritespinelAntrimNorthern Ireland
Type
Research Article
Information
Mineralogical Magazine , Volume 49 , Issue 354 , December 1985 , pp. 663 - 670
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1985

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Footnotes

*

Present address: 19 Beaufort Road, Ealing, London W5 3EB.

†

Present address: BGS, Keyworth, Nottingham NG12 5GG.

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