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A blue sodic beryl from southeast Ireland

Published online by Cambridge University Press:  05 July 2018

I. S. Sanders  and
D. H. Doff
I. S. Sanders
Affiliation:
Department of Geology, Trinity College, Dublin 2, Ireland
D. H. Doff
Affiliation:
Department of Geology, Trinity College, Dublin 2, Ireland
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Abstract

Deep azure-blue beryl is reported from veins in Upper Devonian conglomerate from southeast Ireland. Microprobe analysis, Mössbauer spectroscopy and loss on ignition suggest an unusual chemistry with an exceptionally high degree of substitution of Fe and Mg for Al, and extreme amounts of Na and water held within channel sites in the structure. The calculated structural formula is:

Refractive indices (1.603 and 1.595) and the cell edge, a, (9.292 Å) are also unusually high. Colourless beryl from the same locality, some of which forms cores to blue beryl prisms, has less octahedral substitution and a lower Fe/Mg ratio. The origin of the beryl is tentatively linked to contemporaneous volcanic activity.

Keywords

berylMössbauer spectroscopysodiumIreland
Type
Mineralogy and Geochemistry
Information
Mineralogical Magazine , Volume 55 , Issue 379 , June 1991 , pp. 167 - 172
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1991

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References

Abrecht, J. and Hänni, H. (1980) Eine Beryll-Phenakit (Be2SiO4)-Paragenese aus dem Rotondo Granit. Schweiz. Mineral. Petrog. Mitt., 59, 1–4.Google Scholar
Aines, R. D. and Rossman, G. R. (1984) The high-temperature behaviour of water and carbon dioxide in cordierite and beryl. Amer. Mineral., 69, 319-27.Google Scholar
Aurisicchio, C., Fioravanti, G., Grubesi, O., and Zanazzi, P. F. (1988) Reappraisal of the crystal chemistry of beryl. Ibid. 73, 826-37.Google Scholar
Brown, G. E. Jr. and Mills, B. A. (1986) High-temperature structure and crystal chemistry of hydrous alkali-rich beryl from the Harding pegmatite, Taos County, New Mexico. Ibid., 71, 547-56.Google Scholar
Capewell, J. G. (1957) The stratigraphy and sedimentation of the Old Red Sandstone of the Comeragh Mountains and adjacent areas. County Waterford, Ireland. Q. J. Geol. Soc. London, 112, 393.CrossRefGoogle Scholar
Deer, W. A., Howie, R. A., and Zussman, J. (1986) Disilicates and Ring Silicates (Rock-forming Minerals, volume 1 B), Second Edition. Longman, London and John Wiley and Sons, New York. 629 pp.Google Scholar
Fontan, F. and Fransolet, A. M. (1982) Le béryl bleu riche en Mg, Fe et Na dans la mine de Lassur, Ariège, France. Bull. Minéral, 105, 615-20.CrossRefGoogle Scholar
Franz, G., Grundmann, G., and Ackermand, D. (1986) Rock-forming beryl from a regional metamorphic terrain (Tauern window, Austria). Tschermaks Mineral. Petrog. Mitt., 35, 167-92.CrossRefGoogle Scholar
Goldman, D. S., Rossman, G. R., and Parkin, K. M. (1978) Channel constituents in beryl. Phys. Chem. Minerals, 3, 225-35.CrossRefGoogle Scholar
Hawthorne, F. C. and Černý, P. (1977) The alkali-metal positions in Cs-Li beryl. Canad. Mineral. 15, 414-21.Google Scholar
Jahns, R. H. and Ewing, R. C. (1977) The Harding Mine, Taos County, New Mexico. Mineral. Record, 8, 115-26.Google Scholar
Keller, P. (1981) Emeralds of Colombia. Gems and Gemology, 17, 80–92.CrossRefGoogle Scholar
Penney, S. R. (1978) Devonian lavas from the Comeragh Mountains, County Waterford. Earth Set, Royal Dublin Soc, 1, 71-6.Google Scholar
Penney, S. R. (1980) A new look at the Old Red Sandstone succession of the Comeragh Mountains, County Waterford. Ibid. 3, 155-78.Google Scholar
Schaller, W. T., Stevens, R. E., and Jahns, R. H. (1962) An unusual beryl from Arizona. Amer. Mineral, 47, 672-99.Google Scholar
Statham, P. J. (1976) A comparative study of tech-niques for quantitative analysis of X-ray spectra obtained with a Si(Li) detector. X-Ray Spectrometry, 5, 16–28.CrossRefGoogle Scholar
Sweatman, T. R. and Long, J. V. P. (1969) Quantitative electron-probe microanalysis of rock-forming minerals. J. Petrol, 10, 332-79.CrossRefGoogle Scholar
Watters, W. A. (1963) Zoned blue beryl from the Canaan area. Pikikiruna Range, Nelson. New Zeland J. Geol Geophys., 6, 715-17.CrossRefGoogle Scholar