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Hyalotekite, (Ba,Pb,K)4(Ca,Y)2Si8(B,Be)2(Si,B)2O28F, a tectosilicate related to scapolite: new structure refinement, phase transitions and a short-range ordered 3b superstructure

Published online by Cambridge University Press:  05 July 2018

A. G. Christy ,
E. S. Grew ,
S. C. Mayo ,
M. G. Yates  and
D. I. Belakovskiy
A. G. Christy
Affiliation:
Research School of Chemistry, Australian National University, GPO Box 414, Canberra, ACT 2601, Australia
E. S. Grew
Affiliation:
Department of Geological Sciences, 5711 Boardman Hall, University of Maine, Orono, Maine 04469-5711, USA
S. C. Mayo
Affiliation:
Research School of Chemistry, Australian National University, GPO Box 414, Canberra, ACT 2601, Australia
M. G. Yates
Affiliation:
Department of Geological Sciences, 5711 Boardman Hall, University of Maine, Orono, Maine 04469-5711, USA
D. I. Belakovskiy
Affiliation:
A. E. Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18(2), Moscow 117071, Russia
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Abstract

Hyalotekite, a framework silicate of composition (Ba,Pb,K)4(Ca,Y)2Si8(B,Be)2 (Si,B)28F, is found in relatively high-temperature (⩾ 500°C) Mn skarns at Långban, Sweden, and peralkaline pegmatites at Dara-i-Pioz, Tajikistan. A new paragenesis at Dara-i-Pioz is pegmatite consisting of the Ba borosilicates leucosphenite and tienshanite, as well as caesium kupletskite, aegirine, pyrochlore, microcline and quartz. Hyalotekite has been partially replaced by barylite and danburite. This hyalotekite contains 1.29–1.78 wt.% Y2O3, equivalent to 0.172–0.238 Y pfu or 8–11% Y on the Ca site; its Pb/(Pb+Ba) ratio ranges 0.36–0.44. Electron microprobe F contents of Långban and Dara-i-Pioz hyalotekite range 1.04–1.45 wt.%, consistent with full occupancy of the F site. A new refinement of the structure factor data used in the original structural determination of a Långban hyalotekite resulted in a structural formula, (Pbl.96Bal.86K0.18)Ca2(B1.76Be0.24)(Sil.56B0.44)Si8O28F, consistent with chemical data and all cations with positive-definite thermal parameters, although with a slight excess of positive charge (+57.14 as opposed to the ideal +57.00). An unusual feature of the hyalotekite framework is that 4 of 28 oxygens are non-bridging; by merging these 4 oxygens into two, the framework topology of scapolite is obtained. The triclinic symmetry of hyalotekite observed at room temperature is obtained from a hypothetical tetragonal parent structure via a sequence of displacive phase transitions. Some of these transitions are associated with cation ordering, either Pb–Ba ordering in the large cation sites, or B–Be and Si–B ordering on tetrahedral sites. Others are largely displacive but affect the coordination of the large cations (Pb, Ba, K, Ca). High-resolution electron microscopy suggests that the undulatory extinction characteristic of hyalotekite is due to a fine mosaic microstructure. This suggests that at least one of these transitions occurs in nature during cooling, and that it is first order with a large volume change. A diffuse superstructure observed by electron diffraction implies the existence of a further stage of short-range cation ordering which probably involves both (Pb,K)–Ba and (BeSi,BB)–BSi.

Keywords

hyalotekitescapolitestructure refinementLångbanSwedenDara-i-PiozTajikistan
Type
Research Article
Information
Mineralogical Magazine , Volume 62 , Issue 1 , February 1998 , pp. 77 - 92
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1998

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References

Baur, W.H. (1981) Interatomic distance predictions for computer simulation of crystal structures. In Structure and Bonding in Crystals II, (Navrotsky, A. and O'Keeffe, M., eds), Academic Press, New York, pp. 31–52.CrossRefGoogle Scholar
Belakovskiy, D.I. (1991) Die seltenen Mineralien von Dara-i-Pioz im Hochgebirge Tadshikistans. Lapis, 16(12), 42–8.Google Scholar
Brise, N.E. and O'Keeffe, M. (1991) Bond valence parameters for solids. Acta Cryst., B47, 192–7.CrossRefGoogle Scholar
Brown, I.D. and Altermatt, D. (1985) Bond valence parameters obtained from systematic analysis of the inorganic crystal structure database. Acta Cryst., B41, 244–7.CrossRefGoogle Scholar
Christy, A.G. (1995) Isosymmetric structural phase transitions: phenomenology and examples. Acta Cryst., B51, 753–7.CrossRefGoogle Scholar
Christy, A.G., Haines, J. and Clark, S.M. (1992) A Raman spectroscopic and energy-dispersive X-ray diffraction study of the high-pressure phase transitions of sodium hydrogen fluoride. J. Phys. Condensed Matter, 4, 8131–4.CrossRefGoogle Scholar
Grew, E.S., Belakovskiy, D.I., Fleet, M.E., Yates, M.G., McGee, J.J. and Marquez, N. (1993) Reedmergnerite and associated minerals from peralkaline pegmatite, Dara-i-Pioz, southern Tien Shan, Tajikistan. Eur. J. Mineral., 5, 971–84.CrossRefGoogle Scholar
Grew, E.S., Yates, M.G., Belakovskiy, D.I., Rouse, R.C., Su, S.-C. and Marquez, N. (1994) Hyalotekite from reedmergnerite-bearing peralkaline pegmatite, Dara-i-Pioz, Tajikistan, and from Mn skarn, Långban, Värmland, Sweden: a new look at an old mineral. Mineral. Mag., 58, 285–97.CrossRefGoogle Scholar
Haines, J. and Christy, A.G. (1992) Hydrogen bond formation in sodium and potassium hydrosulfides at high pressure. Phys. Rev., B46, 8797–805.CrossRefGoogle Scholar
Lindström, G. (1887) Om hyalotekit från Långban. Öfversigt af Kongliga Vetenskaps-Akademiens Förhandlingar, 589–93.Google Scholar
Moore, P.B., Araki, T. and Ghose, S. (1982) Hyalotekite, a complex lead borosilicate: its crystal structure and the lone-pair effect of Pb (II). Amer. Mineral., 67, 1012–20.Google Scholar
Moore, P.B., Sen Gupta, P.K. and Schlemper, E.O. (1985): Solid solution in plumbous potassium oxysilicate affected by interaction of a lone pair with bond pairs. Nature, 318, 548.CrossRefGoogle Scholar
Nordenskiöld, A. E. (1877) Nya mineralier från Långban. Geologiska Föreningens i Stockholm Förhandlingar, 3, 376–84.CrossRefGoogle Scholar
O'Keeffe, M. and Hyde, B.G. (1981) The role of non-bonded forces in crystals. In Structure and Bonding in Crystals I, (Navrotsky, A. and O'Keeffe, M., eds), Academic Press, New York, pp. 227–54.Google Scholar
Peacor, D.R. and Bluerger, M.J. (1962): Determination and refinement of the structure of narsarsukite, Na2TiOSi4O10 . Amer. Mineral., 47, 539–56.Google Scholar
Pring, A., Din, V.K., Jefferson, D.A. and Thomas, J.M. (1986) The crystal chemistry of rhodizite: a re-examination. Mineral. Mag., 50, 163–72.CrossRefGoogle Scholar
Rouse, R.C. and Peacor, D.R. (1994) Maricopaite, an unusual lead calcium zeolite with an interrupted mordenite-like framework and intrachannel Pb4 tetrahedral clusters. Amer. Mineral., 79, 175–84.Google Scholar
Scott, V. D. and Love, G. (1992) Formulation of a universal electron probe microanalysis correction method. X-Ray Spectrum, 21, 27–35.CrossRefGoogle Scholar
Taylor, W.H. and Náray-Szábo, St. (1931) The structure of apophyllite. Z. Kristallogr. , 77, 146–58.Google Scholar
Watkin, D.J., Carruthers, P.W. and Betteridge, P.W. (1985) CRYSTALS User Guide Chemical Crystallography Laboratory, University of Oxford.Google Scholar