Manganotantalite from Alto do Giz, RN, Brazil
The mineral group tantalite [(Fe, Mn)Ta2O6] is the primary source of the chemical element tantalum. It is chemically similar to columbite, and the two are often grouped together as a semi-singular mineral called coltan or "columbite-tantalite" in many mineral guides. However, tantalite has a much greater specific gravity than columbite (8.0+ compared to columbite's 5.2). Iron-rich tantalite is the mineral tantalite-(Fe) or ferrotantalite and manganese-rich is tantalite-(Mn) or manganotantalite.
Tantalite is also very close to tapiolite. Those minerals have same chemical composition, but different crystal symmetry orthorhombic for tantalite and tetragonal for tapiolite.
Tantalite is black to brown in both color and streak. Manganese rich tantalites can be brown and translucent.
Tantalite has been found in Australia, Brazil, Canada, Colombia (Guainía and Vichada), Egypt, northern Europe, Madagascar, Namibia, Nigeria, Rwanda, the United States (California, Colorado, Maine, and Virginia), and Zimbabwe. Brazil has the world's largest reserve of tantalite (52.1%). In 2006, 75% of world tantalite production came from Australia.
The mining of tantalite causes many ecological and social problems in Democratic Republic of Congo.
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