Original paper

Iron-rich kornerupine in sheared pegmatite from the Wanni Complex, at Homagama, Sri Lanka

Grew, Edward S.; Hiroi, Yoshikuni; Motoyoshi, Yοichi; Kondo, Yuji; Jayatileke, Sarath J. M.; Marquez, Nicholas

European Journal of Mineralogy Volume 7 Number 3 (1995), p. 623 - 636

49 references

published: May 19, 1995
manuscript accepted: Dec 13, 1994
manuscript received: Jun 15, 1994

DOI: 10.1127/ejm/7/3/0623

BibTeX file

ArtNo. ESP147050703015, Price: 29.00 €

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Abstract Kornerupine occurs sparingly in a sheared pegmatitic vein about 15-20 cm thick and 1-2 m in extent in cordierite gneiss of the Wanni Complex at Homagama, 17 km SE of Colombo, Sri Lanka. The pegmatite consists of dominant quartz, microcline, and cordierite, minor plagioclase, and traces of kornerupine, tourmaline, dumortierite, muscovite, biotite, chlorite, garnet, andalusite, siderite-magnesite, monazite, zircon, apatite, gahnite, magnetite, ilmenite, rutile, ilmenorutile(?), and pyrite; sillimanite occurs elsewhere in the pegmatite. Kornerupine contains 14.4-15.0 wt% Fe as FeO and 0.14-0.18 wt% BeO, among the highest values reported for this mineral. The kornerupine-bearing portion of the pegmatite contains 44 ppm Be, 30 ppm B, and 12 ppm Cs, that is, the trace-element enrichment that one might expect in a granitic pegmatite. Two periods of crystallization are inferred, which correspond to the following stable assemblages: (1) cordierite ± garnet + early andalusite (± sillimanite) + K-feldspar + oligoclase + quartz, possibly at T > 540°C, P 0.8 (for P ≈ 3 kbar) during metamorphic recrystallization. Distinct kornerupine + cordierite (XFC = 0.31-0.33) + quartz and tourmaline + andalusite + K-feldspar + cordierite (XFe = 0.37) + quartz domains developed during (1). At the > 540°C temperatures inferred for crystallization of the Homagama pegmatite, kornerupine was probably not stable with plagioclase and quartz, and thus crystallized from the pegmatitic melt with cordierite in isolation from plagioclase


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