Sangu garnet deposit, Eastern Province, Zambia


Authors: Seifert AV, Vrána S

Published in: Bulletin of Geosciences, volume 78, issue 1; pages: 3 - 8; Received 2 September 2002; Accepted in revised form 20 November 2002;

Keywords: gems, garnet deposits, granulites, veins, pyrope, almandine, Zambia,

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Gem-quality garnet at the Sangu deposit occurs in plagioclase segregation veins confined to mafic granulite, as nodular crystals up to 10 cm in diameter. The colour is commonly red to brownish red in transmitted light, with a moderate brown hue. Faceted stones up to two-carats size have a pleasant strong red colour in incident light, but larger pieces show typically dark tone. Sangu garnet is pyrope-almandine with 46-47 mol% Prp, 39-40 mol% Alm, 9-10 mol% Grs, 2-3 mol% Adr, and 0.10 wt% TiO2. Indices of refraction are 1.7597-1.7632 and specific gravity ranges from 3.87 to 3.94. This garnet is characterized by the presence of abundant acicular rutile crystals. Mine production primarily consists of fractured pieces 1-3 cm in size, 0.5-2 grams in weight.