Generally, the abundance of accessory minerals (topaz, cassiterite, columbite-tantalite
, microlite, and Li-Be phosphates) tends to increase upward from the B3 to the B1 facies, the latter being the most evolved.
"If they are looking for columbite-tantalite
(coltan) or other rare earths, they are generally found in these soils, which means you have to remove them in order to extract these minerals.
O coltan (columbite-tantalite
) e a denominacao utilizada para o minerio de tantalite nao processado da RDC, nome que se popularizou por ser usado nesta regiao (NEST, 2011).
The company's Green Compliance Service Center in Asia actively surveys suppliers to determine whether any Conflict Minerals (columbite-tantalite
[coltan]; cassiterite [tin]; gold; wolframite [tungsten]; or their derivatives) used to make product components were procured from "covered countries" such as Angola, Burundi and Rwanda.
Hashmi reported that there were two main mining areas for tourmaline near Numbi; at both localities, columbite-tantalite
minerals are recovered as a by-product.
I am in agreement with your assessment, especially when we learn that it is estimated that the Democratic Republic of the Congo has 64% of the world's coltan (columbite-tantalite
) which is used in constructing modern electronic devices.
The following conflict minerals are defined in the SEC's final rule: columbite-tantalite
(coltan), cassiterite, gold, wolframite, and their derivatives (currently limited to tantalum, tin, and tungsten, which are extracted from coltan, cassiterite, and wolframite, respectively), "or any other minerals or their derivatives determined by the Secretary of State to be financing conflict in the Covered Countries" (SEC Final Rule 34-67716, p.
More accurately termed columbite-tantalite
, but universally known by its abbreviation 'coltan', author Michael Nest explodes many of the myths that have grown around this controversial metal.
The main minerals at issue are columbite-tantalite
According to the United States Geological Survey, Africa holds 90 percent of the world's deposits of cobalt, 90 percent of its platinum, 50 percent of its gold, 98 percent of its chromium, 64 percent of its manganese, 33 percent of its uranium, and 80 percent of its columbite-tantalite
. The continent also ranks first or second in world reserves of bauxite, industrial diamonds, phosphate rock, vermiculite and zirconium.