Waterfall of Salto da Onça, region of Serra da Carnaíba, Bahia, Brazil. August 10, 2008.

THE REGION OF EMERALD CARNAÍBA

Mineralization: EMERALD


HISTORY
REGION OF EMERALD CARNAÍBA .

Discovered in 1963 in the 80s was the main region in Brazil for production of emeralds. The area of the mine covers 4 hectares. This area comprises several sections which produce the yolk is the most important of the garimpo Carnaíba de Cima, (responsible for more than 60% of production) in the 70's and 80 (Moreira & Santana 1982). Other passages that stand out are the goldfields of: Carnaíba de Baixo, Gaviao, Bode, Lagarta, Braulia and Marota.

LOCATION

The mine is located near Carnaíba of the Municipalities of Saúde and Pindobaçu To achieve this garimpo go to entrocamento linking and municipality of Antônio Gonçalves Campo Formoso. From this follow the BA-374 until the municipality Pindobaçu, then continue for another 9 km towards the town of Saúde to achieve road that will access Garimpo of Carnaíba.

GEOLOGY

The geology is shown in series with adaptations Geological Tours: Embasamento Arqueno-Proterozóico Bottom of the San Francisco craton in northeastern Bahia - Misi & Silva (1998). This publication is shown that the Garimpo of Carnaíba is located on a granitic body that Rudowski et al (1987) described how the intrusion of a small circular shape (Fig. 1 - Silva & Misi (op. cit)), with about 6 km in diameter, located in the mountain structure antiforme of Jacobina. The intrusive nature of the body, according to the authors mentioned above, is marked by the presence of numerous enclaves of quartz rocks of the hills and rocks of Jacobina ultramáficas cromitíferas the context of emhasamento. Below is shown the simplified geological map of the region where is located the Garimpo of Carnaíba (Rudowski et al 1987 modified to Couto et al 1978):

The granite of Carnaiba is described by Rudowski et al (op. cit.) As one to two mica granite, porfiróide associated with pegmatitic veins accompanied occasionally by tourmaline. Pegmatitic bodies come into contact with ultramáficas serpentinizadas developing an area rich in phlogopite, which grains to poor areas increasingly enriched in phlogopite and serpentine to talc. The mineralization of beryl (emerald) occur close to and within the pegmatitic veins flogopititos. These authors also describe the presence of molihdenita, scheelita, tourmaline, and some sulfides (chalcopyrite, pyrite and pirrotita).

Griffon et al (1967) Rudowski et at (op. cit.) Argue that the genesis of the mineralization is related to the assimilation of Cr ultramáficas by crystals of beryl and the Be and Mo would have been brought by hydrothermal fluids resulting from granitic magmatism.

In case of visiting the region suggest the publication Embasamento Arqueno-Proterozóico Bottom of the Sao Francisco craton in northeastern Bahia de Silva & Misi (1998) because it contains all the tips needed to tour the region and a good vision on the regional geological features.





BIBLIOGRAPHY

COUTO, PA; SAMPAIO, AR; GIL, CAA; LOUREIRO, HC; ARCANJO, JB; FERNANDES FILHO, J. GUIMARÃES, JT; CAMPELO, R (1978) Serra de Jacobina Project. Report final.Salvador, CPRM, Vol.1 Agreement DNPM / CPRM.

Griffon, JC (1967) Introduction to the geological map (1:1000.000) of the central part of the Sierra de Jacobina (Bahia). XXI Congr. Bras. Of Geology, Curitiba. Paraense Bol. of Geosciences, 76, 33-34.

MOREIRA, M.D. & SANTANA, A. (1982) Geology and mineralization in the gold mining of Carnaíba, Bahia. In: XXXII Congr. Brasileiro de Geologia, Salvador, SBG, Anais, vol. 3, 852-861.

RUDOWSKI, L. ; GIULIANI, G., Sabato, P. (1987) Les phlogopitites the Emeraude du voisinage des Granites Carnaíba et de Campo Formoso (Bahia, Brézil): an example of minéralisation protérozoique to Be, Mo W et dans des ultrabasiques métassomatisées. C. R. Acad. Sc. Paris, t. 304, Series II, No 18, 1129-1134.

SILVA, M. of G. of & MISI, A. (1988) Embasamento Arqueno-Proterozóico Bottom of the Sao Francisco craton, in northeastern Bahia - Geology and Mineral Deposits. Tours Geological Series. Superintendent of Geology and Mineral Resources, 164 p.

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