Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-27T08:24:02.312Z Has data issue: false hasContentIssue false
  • English
  • Français

The thermal transformation of datolite, CaBSiO4(OH), to boron-melilite

Published online by Cambridge University Press:  05 July 2018

J. Tarney ,
A. W. Nicol  and
Giselle F. Marriner
J. Tarney
Affiliation:
Departments of Geology, Minerals Engineering, and Physics, respectively, University of Birmingham
A. W. Nicol
Affiliation:
Departments of Geology, Minerals Engineering, and Physics, respectively, University of Birmingham
Giselle F. Marriner
Affiliation:
Departments of Geology, Minerals Engineering, and Physics, respectively, University of Birmingham
Get access Rights & Permissions [Opens in a new window]

Summary

A kinetic and X-ray study of the dehydroxylation of datolite, CaBSiO4(OH), has shown that the decomposition occurs very rapidly above 700°C in air, with an activation energy for the reaction of the order of 200 kcal mole −1. The transformation is topotactic, the dehydroxylated phase being tetragonal with a 7·14 Å, c 4·82 Å, and particularly well formed even at the lowest temperatures of decomposition. Single-crystal studies have shown that two orientations of the new phase exist and that the original a of datolite becomes the unique axis of the tetragonal phase while the tetragonal a axes are oriented either parallel to or at 45° to the b and c axes of datolite. The new phase appears to be a boron-containing analogue of the melilite structure, composition Ca2SiB2O7, but is metastable. The basic sheet structure is preserved during the transformation but a reorganization of the tetrahedral layer from the 4- and 8-membered rings of datolite to the 5-membered rings of the new phase is involved, together with effective removal of protons and some silicon. The transformation can be explained in terms of an inhomogeneous reaction mechanism involving migration of calcium and boron into the new phase domains and counter-migration of silicon and protons, but with only minor readjustment of oxygens. The high activation energy of the reaction is explicable in terms either of the effort necessary to remove silicon from the domains of the new phase or of the difficulty of moving the large calcium ions through a relatively close-packed structure.

Type
Research Article
Information
Mineralogical Magazine , Volume 39 , Issue 302 , June 1973 , pp. 158 - 175
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1973

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.)

References

Anderson, (P. J.) and Horlock, (R. F.), 1962. Trans. Faraday Soc., 58, 478.CrossRefGoogle Scholar
Bakakin, (V. V.), Belov, (N. V.), Borisov, (S. V.), and Solovyeva, (L. P.), 1970. Amer. Min., 55, 1167.Google Scholar
Ball, (M. C.) and Taylor, (H. F. W.), 1963. Min. Mag., 33, 467.Google Scholar
Bartram, (S. F.), 1969. Acta Cryst. B25, 791.CrossRefGoogle Scholar
Brindley, (G. W.), 1963. Progr. Ceram. Sci., 3, 1.Google Scholar
Brindley, (G. W.) Achar, (B. N. N.), and Sharp, (J. H.), 1967b. Amer. Min., 52, 1697.Google Scholar
Brindley, (G. W.) and Hayami, (R.), 1965. Min. Mag., 35, 189 Google Scholar
Brindley, (G. W.) and Nakahira, (M.), 1958. Clays and Clay Minerals, 5th Nat. Conf.(1956), 266.Google Scholar
Brindley, (G. W.) 1959. Journ. Amer. Ceram. Soc., 42, 311.CrossRefGoogle Scholar
Brindley, (G. W.) Sharp, (J. H.), Patterson, (J. H.), and Achar (B. N. N.), 1967a. Amer. Min., 52, 201.Google Scholar
Carter, (R. E.), 1961. Journ. Chem. Phys., 34, 2010.CrossRefGoogle Scholar
Christ, (G. L.), 1959. Amer. Min., 44, 176.Google Scholar
Dent, (L. S.) and Taylor (H. F. W.), 1956. Acta Cryst., 9, 1002.CrossRefGoogle Scholar
Eberhart, (J. P.), 1963. Comptes Rend. Acad. Sci. Paris, 256, 3711.Google Scholar
Flint, (E. P.) and Wells, (L. S.), 1936. Journ. Res. Nat. Bur. Standards, 17, 734.CrossRefGoogle Scholar
Freeman, (A. G.) and Taylor (H. F. W.), 1960. Silikattechnik, 11, 390.Google Scholar
Gard, (J. A.) and Taylor (H. F. W.), 1958. Amer. Min., 43, 1.Google Scholar
Gard, (J. A.) 1960. Acta Cryst., 13, 785.CrossRefGoogle Scholar
Garner, (W. E.), 1955. In Garner, (W. E.), ed. Chemistry of the solid state, 213. Butterworths (London).Google Scholar
Gordon, (R. S.) and Kingery, (W. D.), 1967. Journ. Amer. Ceram. Soc., 50, 8.CrossRefGoogle Scholar
Gregg, (S. J.) and Razouk, (R. I.), 1949. Journ. Chem. Soc., Suppl. vol. S36.CrossRefGoogle Scholar
Hetherington, (G.), Jack, (K. H.), and Kennedy, (J. C.), 1964. Phys. Chem. Glasses, 5, 130.Google Scholar
Ito, (T.) and Mori, (H.), 1953. Acta Cryst., 6, 24.CrossRefGoogle Scholar
Johansson, (G.), 1959. Ibid. 12, 522.CrossRefGoogle Scholar
Johnson, (H. B.) and Kessler, (F.), 1969. Journ. Amer. Ceram. Soc., 52, 199.CrossRefGoogle Scholar
Katz, (G.), Nicol, (A. W.), and Roy, (R.), 1969. Zeits. Krist., 130, 388.CrossRefGoogle Scholar
Lacy, (E. D.), 1965. In Pitcher, (W. S.) and Flinn, (G. W.), eds. Controls of Metamorphism, Geol. Journ., Special Issue no. 1, 140.Google Scholar
Megaw, (H. D.), 1952. Acta Cryst., 5, 477.CrossRefGoogle Scholar
Megaw, (H. D.) and Kelsey, (C. H.), 1956. Nature, 177, 390.CrossRefGoogle Scholar
Murray, (P.) and White, (J.), 1955. Brit. Ceram. Soc. Trans., 54, 137.Google Scholar
Nakahira, (M.), 1964. Clays and Clay Minerals, 12th Nat. Conf. (1963), 20.Google Scholar
Nicol, (A. W.), 1962. Ph.D. Thesis, Aberdeen Univ.Google Scholar
Nicol, (A. W.) 1964. Clays and Clay Minerals, 12th Nat. Conf. (1963), 9.Google Scholar
Nicol, (A. W.) 1971. Acta Cryst. B27, 469.Google Scholar
Pant, (A. K.) and Cruickshank (D. J. W.), 1967. Zeits. Krist., 125, 286.CrossRefGoogle Scholar
[Pavlov, (P. V.) and Belov, (N. V.)] (Crystallography) 4, 324.Google Scholar
Roy, (R.), 1956. Journ. Amer. Ceram. Soc., 39, 145.CrossRefGoogle Scholar
Sharp, (J. H.), Brindley, (G. W.), and Achar, (B. N. N.), 1966. Ibid. 49, 379.CrossRefGoogle Scholar
Smith, (J. V.), 1953. Amer. Min., 38, 643.Google Scholar
Taylor, (H. F. W.), 1955. Acta Cryst., 8, 440.CrossRefGoogle Scholar
Taylor, (H. F. W.) 1960. Journ. Appl. Chem., 10, 317.CrossRefGoogle Scholar
Taylor, (H. F. W.) 1961. Progr. Ceram. Sci., 1, 89.Google Scholar
Taylor, (H. F. W.) 1962a. Clay Min. Bull., 5, 45.CrossRefGoogle Scholar
Taylor, (H. F. W.) 1962b. Amer. Min., 47, 932.Google Scholar
Taylor, (H. F. W.) 1957. Clays and Clay Minerals, Sixth Nat. Conf., 101.Google Scholar
Taylor, (H. F. W.) 1959. Min. Mag., 32, 110.Google Scholar
Warren, (B. E.), 1930. Zeits. Krist., 74, 131.Google Scholar
Yvon, (K.), Jeitschko, (W.), and Parthe, (E.), 1969. Tech. Rept., Lab. for Research on Structure of Matter Univ. of Pennsylvania.Google Scholar