Spessartine Garnets in a Manganiferous Carbonate Formation from Nsuta, Ghana |
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| Authors: | Frank K Nyame Katsuo Kase Masahiro Yamamoto |
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| Institution: | Department of Earth Sciences, Okayama University, 3–1–1 Tsushima Naka, Okayama 700–0082, Japan;Graduate School of Natural Science and Technology, Okayama University, 3–1–1 Tsushima Naka, Okayama 700–0082, Japan |
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| Abstract: | Abstract: Manganese carbonate ore beds and host rock manganiferous phyllites at the Nsuta mine, western Ghana, contain well developed garnet crystals. Individual crystals are idioblastic, sometimes porphyroblastic, and homogeneous, and are associated with rhodochrosite (with or without kutnahorite), quartz and muscovite. The conspicuous absence of chlorite in garnet-rich assemblages, and of garnet in chlorite-rich rocks, suggest chemical constraints may have been important in the formation of the two minerals. Gondite bands within carbonate ores are interpreted to have resulted from localised processes in which manganese carbonates, in environments rich in alumino-silicate minerals, may have been completely exhausted during metamorphic reactions. |
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| Keywords: | Garnet Spessartine Rhodochrosite Kutnahorite Manganese Nsuta Ghana Birimian |
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