Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2025-01-03T23:29:30.187Z Has data issue: false hasContentIssue false
  • English
  • Français

Order-disorder in sapphirine

Published online by Cambridge University Press:  14 March 2018

Duncan McKie
Duncan McKie*
Affiliation:
Department of Mineralogy and Petrology, Downing Place, Cambridge
Get access Rights & Permissions [Opens in a new window]

Summary

Yellow sapphirine with a doubled b-axis occurs in enstatite-hornblende-sapphirine rocks at the contact between dolomite marble and yoderite-quartz-talc schist on Mautia Hill, Tanganyika. It has refractive indices α 1·725± 0·002, γ 1·732±0·002, 2Vγ66°, pleochroism a pale yellow, β pale lime green, γ pale pinkish orange, and a composition corresponding to Mg3·67Mn0·04Fe2+0·17Ti0·01Fe3+0·33Als·07Si1·75O20·00. Its unit-cell dimensions are approximately a 9·85 Å, b 28·6Å, c 9·96 Å, β 110° 30′, and its diffraction pattern exhibits diffuse streaks parallel to b*, on which lie diffuse intensity maxima representing the relics of certain types of sharp reflexions of normal sapphirine ; this is interpreted as indicative of partial MgAl ordering. The associated enstatite and hornblende have compositions Mg7·58Mn0·02Fe2+0·02Ti0·01Fe3+0·13Al[6]0·25Al0·41[4]Si7·59O24·00 and K0·04Na0·16Ca1·95Mg4·37Mn0·01Fe0·052+Ti0·04Fe0·253+Al0·42[6]Al0·91[4]Si7·09O22·24(OH)1·76respectively and are accompanied by accessory hematite and pseudobrookite. Preliminary heating experiments have demonstrated the transformation of single crystals of partially ordered Mautia sapphirine to single crystals of a defect spinel phase after 48 hours at 1287° C in air; normal disordered Panrimali sapphirine remains unchanged by similar heat treatment.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 33 , Issue 263 , December 1963 , pp. 635 - 645
Copyright
Copyright © 1963, The Mineralogical Society

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

Bøggild, (O. B.), 1954. Medd. Gronland, Bd. 149, no. 3.Google Scholar
Bown, (M.G.) and Gay, (P.), 1958. Zeits. Krist., vol. 111, p. 1.Google Scholar
Boyd, (F.R.) and England, (J.L.), 1960. Ann. Rept. Geophys. Lab., Carnegie Inst. Washington Year Book 59, p. 49.Google Scholar
Deer, (W.A.), Howie, (R.A.), and Zussman, (J.), 1962. Rock forming mineral., vol. 1, Longmans, London.Google Scholar
Fleet, (S.G.) and Megaw, (H.D.), 1962. Acta Cryst., vol. 15, p. 721.Google Scholar
Foster, (W.R.), 1950. Journ. Geol., vol. 58, p. 135.Google Scholar
Gay, (P.), 1953. Min. Mag., vol. 30, p. 169.Google Scholar
Gay, (P.), 1954. Ibid., vol. 30, p. 428.Google Scholar
Gossner, (B.) and Mussgnug (F.),1928. 5∼eues Jahrb. Min., Abt. Beil.-Bd. 58, p. 233.Google Scholar
Kuzel, (H.-J.), 1961. Neues Jahrb. Min., Monats., p. 68.Google Scholar
Lacroix, (A.), 1940. Compt. Rend. Acad. Sci. Pari., vol. 210, p. 193.Google Scholar
Lacroix, (A.), and DE Gramont, (A.), 1921. Bull. Soc. frang. Min., vol. 44, p. 67.Google Scholar
Laves, (F.) and Goldsmith, (J.R.), 1954. Acta Cryst. vol. 7, p. 131.Google Scholar
Mckie, (D.), 1959. Min. Mag. vol. 32, p. 282.Google Scholar
Mckie, (D.), 1963. Ibid., vol. 33, p. 563.Google Scholar
Segnit, (E.R.), 1957. Ibid., vol. 31, p. 690.Google Scholar
Sørrensen, (H.), 1955. Medd. Gronlan., vol. 137, no. 1, p. 3.Google Scholar
Turner, (F.J.) 1958. In Mere. Geol. Soc. Amer., no. 73, p. 199.Google Scholar
Vogt, (T.), 1947. Bull. Comm. g∼ol. Finlande, no. 140, p. 15.Google Scholar
Warren, (C.H.), 1912. Amer. Journ. Sci., ser.., vol. 33, p. 263.Google Scholar
(A.J. C.), Wilson, 1949. X-ray optics. Methuen, London.Google Scholar