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A number of precious stones and minerals in Tanzania are found either just on the ground surface or unexplored
inside the earth. Principally, those found at the surface differ in their source of origin from those found inside the
earth. Some of these stones are coming from the rocks in their present locations (primary deposits) while others are
transported from other places (secondary deposits). The mechanism of transportation may be rivers, sea or wind. The
distribution of these valuable stones is geographically irregular in Tanzania and in some of the regions the deposits
are higher compared than others. In several parts of the country such information is completely unavailable and
in many cases unexplored. In order to provide this information to the decision makers and investors, Wavelength
Dispersive X-ray Fluorescence (WDXRF) Analysis has been used with objective of identifying the composition
of some of these stone and rock samples. The samples identified and reported in this paper include: Iron ore,
Green Aventurine, Amethyst, Red Garnet, Sapphire nuts, Green Opal, Blue Kymete, Black Tormaline, White opal,
Aquamarine and Granite. The samples were prepared as pellets after mixing with boric acid or fused as discs for
analysis. Typical results for the Iron Ore in % are SiO2 (0.97), Al2O3 (0.57), Fe2O3 (77.5), MnO (0.35), MgO (0.35),
CaO (0.16), Na2O (< 0.01), K2O (0.04), TiO2 (19.1), P2O5 (< 0.01), SO3 (0.14) and that of the Amethyst SiO2 (97.8),
Al2O3 (0.11), Fe2O3 (1.37), MnO (< 001), MgO (< 0.01), CaO (< 0.01), Na2O (< 0.01), K2O (< 0.01), SO3 (0.33). The
results show that Tanzania is a very rich country in minerals but are currently unexplored either because of lack of
information or investment capital. |
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