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Rem: Revista Escola de Minas

Print version ISSN 0370-4467

Abstract

CHAVES, Mario Luiz de Sá C.; BRANDAO, Paulo Roberto Gomes; GIRODO, Antonio Carlos  and  BENITEZ, Leila. The Canastra-1 kimberlite (Sao Roque de Minas town, MG): geology, mineralogy and diamond reserves. Rem: Rev. Esc. Minas [online]. 2008, vol.61, n.3, pp. 357-364. ISSN 0370-4467.  http://dx.doi.org/10.1590/S0370-44672008000300014.

The research on the primary diamond sources in Brazil started in the 1960 years and had its highest achievement with the discovery of the mineralized Canastra-1 kimberlite which is the first Brazilian primary deposit having economic contents. This pipe surfaces in the Serra da Canastra (Canastra Range) near the sources of the São Francisco River. The intrusion is made up of two blows lined along NE-SE, which is the region's structural trend defined in the metasedimentary rocks of the Canastra Group. The smaller blow is nearly circular with an area of approximately 0.8 ha and has only negligible diamond content. The SE blow has almost 1.0 ha and is mineralized with an average content of 12 to 18 ct/100 tonnes of rock. There are also significant differences in the petrographic facies of the two bodies, which is homogeneous in the NW blow while the SE blow is heterogeneous, with the occurrence of a mixture of several facies. The short distance between the blows justifies the assumption that they join in depth, therefore being apophyses of the same intrusion. The mineral chemistry of the indicators showed a strong resemblance with some diamondiferous African kimberlites. Data from experimental mining indicated an excellent quality for this kimberlite's diamonds, with US$180-200/ct estimated average value.

Keywords : Kimberlite; diamond; mineral research; Canastra-1 pipe.

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