An Intergrowth of Calcic Labradorite in a Plagioclase-Quartz-Biotite Gneiss from Broken Hill, New South Wales

Evan R. Phillips, Bryan E. Chenhall, Ian J. Stone and J. W. Pemberton

Department of Geology, University of Wollongong, Wollongong, N.S.W. 2500, Australia

Summary: Compositions of An₆₁ and An_69·5 have been determined for two domains in plagioclase from a gneiss. Optical properties indicate that the same compositions apply respectively for an intergrowth of ‘matrix’ and lamellae found in zones between the domains. The intergrowth appears to span the composition range between the Bøggild and Huttenlocher intergrowths.

Mineralogical Magazine; December 1977 v. 41; no. 320; p. 469-471; DOI: 10.1180/minmag.1977.041.320.07
© 1977, The Mineralogical Society
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