| Reference Type | Journal (article/letter/editorial) |
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| Title | Hibonite and coexisting zoisite and clinozoisite in a calc-silicate granulite from southern Tanzania |
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| Journal | Mineralogical Magazine | ISSN | 0026-461X |
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| Authors | Maaskant, P. | Author |
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| Coolen, J. J. M. M. M. | Author |
| Burke, E. A. J. | Author |
| Year | 1980 (December) | Volume | 43 |
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| Issue | 332 |
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| Publisher | Mineralogical Society |
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| Download URL | https://rruff.info/doclib/MinMag/Volume_43/43-332-995.pdf+ |
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| DOI | doi:10.1180/minmag.1980.043.332.07Search in ResearchGate |
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| Generate Citation Formats |
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| Mindat Ref. ID | 3188 | Long-form Identifier | mindat:1:5:3188:6 |
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| GUID | 0 |
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| Full Reference | Maaskant, P., Coolen, J. J. M. M. M., Burke, E. A. J. (1980) Hibonite and coexisting zoisite and clinozoisite in a calc-silicate granulite from southern Tanzania. Mineralogical Magazine, 43 (332) 995-1003 doi:10.1180/minmag.1980.043.332.07 |
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| Plain Text | Maaskant, P., Coolen, J. J. M. M. M., Burke, E. A. J. (1980) Hibonite and coexisting zoisite and clinozoisite in a calc-silicate granulite from southern Tanzania. Mineralogical Magazine, 43 (332) 995-1003 doi:10.1180/minmag.1980.043.332.07 |
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| In | (1980, December) Mineralogical Magazine Vol. 43 (332) Mineralogical Society |
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| Abstract/Notes | SummaryThe third terrestrial occurrence of hibonite is reported from granulite-facies rocks in the Furua Granulite Complex in southern Tanzania. The mineral forms yellowish-brown lath-shaped crystals in a grossular-anorthite rock containing subordinate sphene (clino)zoisite, hercynite, apatite, ilmenite, and corundumilmenite intergrowths.Electron-microprobe analyses indicate a generalized formula (Ca1−xREx)[(Al,Fe3+)12−2a+x(Ti,Si)(Ti,Si)a−x(Fe2+, Mg)a]O19, with RE = Ce + La + Nd, x = 0.2, and a = 0.8. Individual mineral analyses show a cation substitution of Ca + Ti + Fe3+ = RE + 2Al. Relatively high RE and Fe contents represent the main chemical differences with meteoritic hibonite. The hexagonal unit cell has a = 5.61 Å, c = 22.18, in good agreement with the other terrestrial hibonites.Three compositional types of (clino)zoisite are distinguished: 1.8–3.1 wt% Fe2O3 (orthorhombic and monoclinic), 3.9–6.0 wt% Fe2O3 (monoclinic), and 5.8–7.9 wt% Fe2O3 with an average of 6.3 wt% RE2O3 (monoclinic).Thermometric and barometric data for coexisting pyroxenes and garnet from adjacent rocks indicate granulite-facies equilibration conditions of 750 to 850 °C and 6 to 11 kb. During retrogression with increasing partial H2O pressures, hibonite reacted with plagioclase and garnet to form spinel, sphene, and RE-bearing clinozoisite. Corundum-ilmenite inter-growths probably resulted from the breakdown of an Fe-högbomite. |
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