The Merelani Graphite-Tanzanite Deposit, Tanzania: An Exploration Case History

Abstract The Merelani graphite-tanzanite deposit is located in northeast Tanzania, 14 kilometers south of Kilimajaro International Airport and in close proximity to the towns of Moshi and Arusha. The graphite mineralization is hosted by relatively undeformed linear Proterozoic metasedimentary gneisses, several of which have been subjected to hydrothermal alteration resulting in tanzanite mineralization. Exploration work comprised detailed geological mapping coupled with pit and trench channel sampling and a subsequent 1500 meters of diamond drilling. In addition, metallurgical tests have shown the graphite to be of unusually coarse flake size, crystallinity and high purity.
Feasability studies have shown the economic viability of a major coarse flake graphite deposit with the measured resource to 50 meters in excess of 9 million tonnes assaying over 8% graphitic carbon. Production is due to start by the end of the first quarter of 1994 with the processing plant design capacity initially set at 15 000 tonnes per annum.
In addition to graphite production, tanzanite will be produced through selective mining within the graphite open pit in the upper horizon and from underground workings within the lower horizon.
The Merelani graphite-tanzanite deposit will be the first major orebody to be exploited through means of private funding since Tanzania gained independence.
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Summary: The basis of the tomographic velocity imaging technique is briefly described and an application of the method to detect and image a cross-section through a chromite pod is presented. Using the chromite application as an example, the relative costs of tomographic data acquisition and processing are compared with those of diamond drilling to obtain similar resolution. A number of different tomographic survey configurations and the potential role of the method in surface and underground...
Publication: Exploration & Mining Geology
Author(s): B.C. DYER
Issue: 4
Volume: 3
Year: 1994
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Summary: In recent years the Environmental Research Group of the KVI has been developing a number of radiometric techniques that may be employed in mineral sand exploration. These techniques involve: radiometric fingerprinting for assessing sand provenances and mineralogical composition; thermoluminescence for dating and provenance determination of sediments; a towed seabed detector to map seafloors for radiogenic heavy minerals and assessing heavy mineral volumes; and simplified transport mechanism...
Publication: Exploration & Mining Geology
Author(s): R.J. de MEIJER, I.C. TANCZOS, C. STAPEL
Issue: 4
Volume: 3
Year: 1994
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Summary: The Riviera tungsten occurrence in the Cape Province of South Africa was discovered in October 1979 as a result of stream-sediment panned concentrate sampling. The Cape age granite and late Precambrian Malmesbury Group carbonates and chlorite schists which it intrudes and which host the mineralization are covered by between 10 m and 30 m of Tertiary/Recent alluvium and clay. The scheelite/powellite and molybdenite mineralization occurs in a greisenized granite cupola with an overprint of...
Publication: Exploration & Mining Geology
Author(s): P.W.A. WALKER
Issue: 4
Volume: 3
Year: 1994
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Summary: In 1986, anomalous sampling results for heavy minerals were obtained at various sites in Namaqualand on the west coast of the Cape Province. Drilling in 1987 at Graauwduinen penetrated up to 35 meters of heavy mineral-bearing Tertiary sands which extend several kilometers inland from the coast. The heavy mineral suite includes ilmenite, rutile, leucoxene, zircon and monazite, along with garnet, pyroxene and amphibole. Three deposits are recognized, two of which comprise the resource to be...
Publication: Exploration & Mining Geology
Author(s): G.L. PALMER
Issue: 4
Volume: 3
Year: 1994
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Summary: The Great Dyke extends for 540 km along strike, to unknown depth, and varies in width from 3 km to 11 km. Rb/Sr age determinations gives values of approximately 2470 Ma.
The Dyke consists of a variety of mafic and ultramafic rocks, many altered to serpentinites. These include, from top to bottom, successions of gabbro/norites, pyroxenites, peridotites/harzburgites, and dunites/picrites.
The layers dip in from either margin, steepest at the edges (20°) and flattening toward the central...
Publication: Exploration & Mining Geology
Author(s): D.J. BOWEN
Issue: 4
Volume: 3
Year: 1994
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Summary: Most of the gold in the Late Archean Witwatersrand Basin is of detrital origin but, in its present form, it is metamorphosed. The only relict detrital features preserved are the morphological characteristics of some placer gold particles. Regional burial metamorphism in the shallower and deeper levels of the Witwatersrand Supergroup reached temperatures around 300°C and 350°C at pressures between 2 kbar and 3 kbar, respectively, estimated from phase relations, chlorite-chloritoid exchange...
Publication: Exploration & Mining Geology
Author(s): H.E. FRIMMEL
Issue: 4
Volume: 3
Year: 1994
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Summary: Mineral exploration and research has led to the identification of four types of tungsten mineralization in the NE-trending, largely ensialic, inland branch of the late Proterozoic/early Paleozoic Pan-African Damara Orogen. The mineralization (mainly scheelite) occurs in a terrane (the Central Zone) that is characterized by multiple deformation, greenschist/amphibolite-facies metamorphism and numerous peraluminous S-type granitic and pegmatitic intrusions. The four major types of scheelite...
Publication: Exploration & Mining Geology
Author(s): N.M. STEVEN, J.L. KUYPER, J.M. MOORE
Issue: 4
Volume: 3
Year: 1994
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Summary: Banded iron formation rocks associated with massive sulfide lenses in the Broken Hill Pb-Zn-Cu-Ag deposit in the Namaqualand Metamorpnic Complex, South Africa, were investigated with respect to the geochemistry of manganiferous silicate-rich bands. Two common varieties of these are: amphibole- and garnet-rich iron formation bands. The results reveal that the former are enriched in Fe, Mg, Cu, Co and S. The garnet-rich bands are enriched in Mn, Ca, P, Pb and Ba with significant detrital...
Publication: Exploration & Mining Geology
Author(s): DENNIS HOFFMANN
Issue: 4
Volume: 3
Year: 1994
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Summary: The distribution of mineralized provinces is analyzed on the basis of their genetic link with specific blocks of the earth's crust including ancient platforms, mobile belts and zones of tectonic-magmatic activation. Mobile and fold belts surround the Siberian platform in Russia and the Kaap-vaal craton in South Africa, with decreasing age zoning away from ancient platform margins. The main differences in the geological development of the two cratonic areas are: (1) the long period before the...
Publication: Exploration & Mining Geology
Author(s): A.L. SOKOLOV, R.P. VILJOEN
Issue: 4
Volume: 3
Year: 1994
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Summary: Mineral deposits and prospects of the Pan African Saldanian erogenic belt in the southwestern Cape Province South Africa, are reviewed. Despite the entire absence of operating base or precious metal mines in the area, this study has established at least four metal associations that offer enticing exploration potential.
The poly-phase deformed, low-grade metamorphosed volcano-sedimentary Malmesbury Group constitutes a complex, poorly understood supracrustal sequence that has been loosely...
Publication: Exploration & Mining Geology
Author(s): A. ROZENDAAL, R. SCHEEPERS
Issue: 4
Volume: 3
Year: 1994
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