Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-10T09:10:56.315Z Has data issue: false hasContentIssue false
  • English
  • Français

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
Get access Rights & Permissions [Opens in a new window]

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

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

†

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

References

Appleman, D. E., and Evans, H. T., Jr. (1973) Job 9214. US. Geol. Surv. Contrib. No. 20.Google Scholar
Biggar, G. M. (1971) Phase relationships of bredigite Ca5MgSi3O12 and the quaternary compound (Ca6MgAl8SiO21) in the system CaO-MgO-Al2O3- SiO2 . Cem. Concr. Res. 1, 493-513. (MA 732607).CrossRefGoogle Scholar
Dunham, A. C., and Wilkinson, F. C. F. (1978) Accuracy, precision, and detection limits of energy dispersive electron-microprobe analyses of silicates. X-Ray Spectrom, 7, 50-6. (MA 78-3889).CrossRefGoogle Scholar
Essene, E. (1980) The stability of bredigite and other Ca-Mg silicates. J. Am. Ceram. Soc. 63, 464-6. (MA 81-1415).CrossRefGoogle Scholar
Griffith, A. E., and Wilson, H. E. (1982) Geology of the country around Carrickfergus and Bangor. Mem. Geol. Surv. North. lrel., Sheet 29.Google Scholar
Hey, M. H. (1950) An index of mineral species and varieties arranged chemically. London. British Museum (Natural History).CrossRefGoogle Scholar
Lin, H. C., and Foster, W. R. (1975) Stability relations of bredigite (5CaO·MgO·3SiO2). J. Am. Ceram. Soc. 58, 73. (MA 76-1616).CrossRefGoogle Scholar
Midgley, H. G. (1974) The polymorphism of calcium orthosilicate. Proc. 6th Int. Congr. Chem. Cem. 1, Chemistry of Cement and Clinker, Moscow (1976), 63-8.Google Scholar
Midgley, H. G. and Bennett, M. (1971) A microprobe analysis of larnite and bredigite from Scawt Hill, Larne, Northern Ireland. Cem. Concr. Res. 1, 413-18.CrossRefGoogle Scholar
Moore, P. B., and Araki, T. (1976) The crystal structure of bredigite and the genealogy of some alkaline earth orthosilicates. Am. Mineral. 61, 74-87. (MA 76 2332).Google Scholar
Moseley, D., and Glasser, F. P. (1981) Identity, composition and stability of bredigite and Phase T. Cem. Concr. Res. 11, 559-65.CrossRefGoogle Scholar
Moseley, D. and Glasser, F. P. (1982) Properties and composition of bredigite-structured phases. J. Mat. Sci. 17, 2736-40.CrossRefGoogle Scholar
Saalfeld, H. (1974) Kristallographische Untersuchungen über die Verbindung CaTMgSi4O16 (Phase T) im System Ca2SiO∼-Ca3Mg (SiO4)2 . Bet. Deutsch Keram. Gesell. 51, 295-8.Google Scholar
Sabine, P. A. (1968) Ferrian chlorospinel from Carneal, Co. Antrim. Mineral. Mag. 36, 948-54. (MA 69-577).Google Scholar
Sabine, P. A. (1975) Metamorphic processes at high temperature and low pressure: the petrogenesis of the metasomatized and assimilated rocks of Carneal, Co. Antrim. Phil. Trans. Roy. Soc. A., 280, 225-69. (MA 76-2124).Google Scholar
Sabine, P. A., Beckinsale, R. D., Evans, J. A., and Walsh, J. N. (1982a) Geochemical and strontium-isotope studies of reactions between basic magma, chalk, and flint, and the role of groundwater, in the Carneal Plug, Co. Antrim, Northern Ireland. J. Petrol. 23, 427-46.CrossRefGoogle Scholar
Sabine, P. A., Styles, M. T., and Young, B. R. (1982b) Gehlenite, an exomorphic mineral from Carneal, Co. Antrim, Northern Ireland. Rept. Inst. Geol. Sci. No. 82/1, 61-3.Google Scholar
Schlaudt, C. M., and Roy, D. M. (1966) The join Ca2SiO4CaMgSiO4 . J. Am. Ceram. Soc. 49, 430-2.CrossRefGoogle Scholar
Tilley, C. E., and Vincent, H. C. G. (1948) The occurrence of an orthorhombic high-temperature form of Ca2SiO4(bredigite) in the Scawt Hill contact-zone and as a constituent of slags. Mineral. Mag. 28, 255-71.Google Scholar
Treiman, A. H., and Essene, E. J. (1983) Phase equilibria in the system CaO-SiO2-CO2 . Am. J. Sci. 283 A, 97–120.Google Scholar
Wyllie, P. J., and Haas, J. L., Jr. (1966) The system CaO-SiO2-CO2-H2O. II: The petrogenetic model. Geochim. Cosmochim. Acta, 30, 525-43.CrossRefGoogle Scholar