Sign In

CBMM
CBMM - English

Yes

​​Country Rock
The geological formation known as the Ibiá Group hosts the Barreiro carbonatite complex and is a pelitic metasedimentary sequence structured in the form of thin rhythmite deposited by the erosion of neoproterozoic magmatic arcs (Seer, 1995). It consists predominantly of mica schists associated with quartzite.

The geological formation known as the Ibiá​ Group hosts the Barreiro carbonatite complex and is a pelitic metasedimentary sequence structured in the form of thin rhythmite deposited by the erosion of neoproterozoic magmatic arcs (Seer, 1995). It consists predominantly of mica schists associated with quartzite.

 

The Barreiro Carbonatite Complex (19°40'S / 46°57'O)
The complex is roughly circular with a surface diameter of approximately 4.5 km. About 90 million years ago its intrusion into quartzites and schists of the Ibi Group caused arching which gave rise to a domed structure with concentric and radial fractures in the country rocks, as well as intense shattering of the quartzites. At the contact zone, fenitization occurred in the form of veins and veinlets mainly composed of sodium amphibole that fill fractures in the quartzite contact zone. Quartz-feldspathic fenites are also present.

Residual Ore (weathered material)
Derived from the primary ore, the residual ore contains nearly 4% bariopyrochlore. Weathering of the primary ore caused volume enrichment of the niobium mineral ore due to its physical preservation compared to other minerals. The ore is friable and the mining operations are carried out in an open pit with no need of explosives. The thickness of the residual ore reaches 250 meters. Currently only the residual ore is mined.

Primary Ore (fresh rock)
The complex is predominantly formed by dolomite carbonatite with subordinate calcite carbonatite and glimmerite (phlogopite-rich rock). The highest niobium contents in the deposit are found in the core of the structure. The primary ore contains carbonatite, phlogopite, magnetite, apatite and pyrochlore. The glimmerite formed by metasomatism of pyroxenite/peridotite only locally present pyroxene and olivine.  The metasomatism occurred during the magmatic, alkaline-carbonatite stage involving alkali-rich fluids. Samples collected from brecciated zones show that pyrochlore is progressively transformed into bariopyrochlore along fractures and at grain boundaries by the substitution of calcium and sodium by barium, probably under the influence of meteoric waters.

Niobium Resources
As of December 2012, mineral reserves in the residual ore totaled nearly 808 million tonnes with an average of 2.3% Nb2O5.

Fresh rock mineral resources were estimated at approximately 1.8 billion tonnes with an average of 1.5% Nb2O5. Evidence collected from drill holes to a depth of 820 meters still intersect mineralized rock, indicating the likelihood that additional reserves probably extend even deeper.

Considering the current market, the mineral resources in Araxá measured in the residual ore and potentially existent in the fresh rock indicate that CBMM will be able to supply the world demand for niobium products for many decades to come.