KORNERUPINE IN MG-AL-RICH GNEISSES FROM NAMAQUALAND, SOUTH-AFRICA - MINERALOGY AND EVIDENCE FOR LATE-METAMORPHIC FLUID ACTIVITY

Journal article

Three kornerupine occurrences are reported in distinctive SiO2-poor, MgO- and Al2O3-rich paragneisses from the Namaqualand Metamorphic Complex in South Africa. Kornerupine coexists stably with phlogopite, cordierite, orthopyroxene, gedrite, sapphirine, sillimanite and plagioclase and, in sapphirine-free rocks, with spinel and corundum. Tourmaline of a texturally older generation than kornerupine is commonly present in the same samples. Ten analysed kornerupines show a variation in total Fe as FeO from 1.8 to 10.9 weight per cent. B2O3 contents are estimated from x-ray data and a few spectrochemical analyses to range from 0.9 to 3.5 weight per cent. There is a strong inverse correlation between B3+ and Al3+. Total iron content has a strong and systematic effect on refractive index, colour and dispersion. Fe and Mg are systematically partitioned with the other minerals, and Mg/(Mg+Fe) ratios increase as follows: spinel

Authors: Waters, D; Moore, J

• Publication status: Published
• Publisher: Springer-Verlag
• Journal: CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
• Volume: 91
• Issue: 4
• Pages: 369-382
• Publication date: 1985-01-01
• DOI: 10.1007/BF00374693
• EISSN: 1432-0967
• ISSN: 0010-7999
• Language: English