Gemology and Geochemistry of Staurolites from the Casa Nova Region, Brazil
DOI:
https://doi.org/10.11137/1982-3908_2024_47_62755Keywords:
Gemological properties, Bahia, GemsAbstract
The properties of minerals used as gemstones could help or even reveal new aspects about the geological evolution of the region where a mineral was found. The objective of this study was the gemological characterization and acquisition of chemical data on staurolites from the city of Casa Nova (Bahia, Brazil). The gemological data are within the normal range for the staurolite mineral, except for the absence of pleochroism, above-average densities in two specimens, and a rare color (intense red) in a sample. The intrinsic part of these gems is in possible correlations involving their properties, such as: color, refractive index, birefringence, relative density, and the amounts of FeO in the samples. The geochemistry of these samples is unusual; FeO and MgO appear in considerably above-average quantities, and Al2O3 is up to 8% below average; the presence of CaO is also rare. Therefore, staurolites from Casa Nova (Bahia) have the potential to be used as gemstones, and their geochemistry combined with the gemology of these samples is a great indication for further studies.
References
Anderson, B.W. 1984, Identificação das Gemas, Livro Técnico S/A, Rio de Janeiro.
Arem, J.E. 2024, Staurolite Value, Price, and Jewelry Information, viewed 12 January 2024, <https://www.gemsociety.org/article/staurolite-jewelry-and-gemstone-information/>.
Barbosa, C.T. 2020, ´Gemologia: a ciência de mil cores´, Terrae Didatica, Campinas, SP, vol. 16, e020016.
Bonewitz, R.L. 2013, Gemas e Pedras Preciosas, DISAL Editora, São Paulo.
Brazil, 2002. Law no. 10.406, 10 January of 2002, viewed 12 January 2024, <http://www.camara.gov.br/sileg/integras/247357.pdf>.
Brito Neves, B.B. & Cordani, U.G. 2013, ´Tectonic Evolution of South America during the late Proterozoic´, Precambrian Research, 1991, vol. 53, pp. 23-40.
Caxito, F. A. & Uhlein, A. 2013, ´Arcabouço Tectônico e Estratigráfico da Faixa Riacho do Pontal, Divisa Pernambuco-Piauí-Bahia´, Revista Geonomos, vol. 21, no. 2, p. 19-37.
CPRM – Serviço Geológico Do Brasil 2014, Casa Nova (SC.24-V-C-II): carta geológica, escala 1:100.000. Salvador: CPRM, 2014. 1 mapa, color, viewed 12 January 2024, < https://rigeo.sgb.gov.br/handle/doc/18454>.
DevMedia. 2013, Código de cor: Infográfico dos códigos das cores em HTM, viewed 06 August 2019, <https://www.devmedia.com.br/codigo-cor-infografico-dos-codigos-das-cores-em-html/37238>.
Dana, J. & Hurlbut Jr., C. 1960, Manual de Mineralogia, 2nd edn, Editorial Reverté, S. A. Barcelona.
Deer, W.A., Howie, R.A. & Zussman, J. 2010, Minerais Constituentes das Rochas uma Introdução, Fundação Calouste Gulbenkian, Lisboa.
Diniz J.A.O. & De Lima J.B. 2008, O Aquífero de Dunas da Região do Médio São Francisco – BA, Águas Subterrâneas.
Flint, E. 1965, Princípios de Cristalografia, Editorial Paz, Moscou.
Franco, R.R. 1961, ´Microscópio e Lupas¬ – Imperfeições das gemas naturais´, Periódico da Associação Brasileira de Gemologia, São Paulo, vol. VI, no. 36, pp. 15-22.
Franco, R.R. & Campos, J.E.S. 1971, As pedras preciosas, Editora da Universidade de São Paulo, São Paulo.
Fujimori, S. & Ferreira, Y.A. 1987, Introdução ao uso do microscópio petrográfico, 2nd edn, Centro Editorial e Didático da UFBA, Salvador.
Hughes, R.W. 2017, Ruby & sapphire: A Gemologist’s guide. Bangkok, RWH Publishing/Lotus Publishing.
Hurlbut Jr., C.S. & Switzer, G.S. 1979, Gemology, John Wiley & Sons, New York.
IBGM – Instituto Brasileiro de Gemas e Metais Preciosos & Gama, J.L.N. 2009, Manual Técnico de Gemas, IBGM/DNPM, Brasília.
Klein, C. & Dutrow, B. 2012, Manual de Ciência dos Minerais, 23th edn, Bookman, Porto Alegre.
Kuyumjiam, R.M. 1998, Kyanite-staurolite ortho-amphibolite from the Chapada Region, Goiás, Central Brazil, viewed 10 December 2023, <https://www.cambridge.org/core/journals/mineralogical-magazine/article/abs/kyanitestaurolite-orthoamphibolite-from-the-chapada-region-goias-central-brazil/7BA264F761A43058A4458D5368B82AD4>.
Machado, F.B. & Nardy, A.J.R. 2016, Mineralogia Óptica, Oficina de Textos, São Paulo.
Mazdab, F.K. 2001, Staurolite, viewed 8 November 2023, <https://www.mindat.org/min-3753.html>.
Nagatani, T. et al. 1987, ´Development of an ultra-high resolution scanning electron microscope by means of a field emission source and inlens system´, Scanning Microscopy, vol. 1, no. 3.
Nassau, K. 1980, Gems Made by Man, Pennsylvania, Chilton Book Company.
Oliveira, A.B. 1967, ´Imperfeições internas cristalinas e sua importância em gemologia´, Periódico da Associação Brasileira de Gemologia, vol. XI, no. 36, pp. 25-37.
Oliveira, I.G., Carneiro, L.S., Saraiva, C.E.R., Mattos, I.C., & Neri, T.F.O. 2020, ´Caracterização Gemológica das Turmalinas de Quixeramobim´, Anuário do Instituto de Geociências – IGEO, vol. 43, no. 1, pp. 207-217.
Roberts, W.L., Campbell, T.J., & Rapp Jr., G.R. 1990, Encyclopedia of Minerals, Van Nostrand Reinhold, New York, USA.
Schumann, W. 2006, Gemas do Mundo, São Paulo, DISAL Editora.
Schumann, W. 2020, Gemstones of the world, Nova York, Sterling Editora.
Skerl, A.C. & Bannister, F.A. 1934, ´Lusakite, a cobalt-bearing silicate from Northern Rhodesia´, Mineralogical Magazine and Journal of the Mineralogical Society, vol. 23, no. 146, pp. 598-606.
Uhlein, A. et al. 2013, ´Estratigrafia e tectônica das faixas neoproterozóicas da porção norte do Cráton do São Francisco´, Revista Geonomos, vol. 19, no. 2.
Vieira, A. T. 2005, CPRM - Serviço Geológico do Brasil. Projeto Cadastro de Fontes de Abastecimento por Água Subterrânea Diagnóstico do Município de Casa Nova, eletronic book, CPRM/PRODEEM, Bahia, Salvador.
Wahlstrom, E.E. 1969, Cristalografia Óptica. Editora da Universidade de São Paulo, São Paulo.
Webster, R. 1981, Gems, London, Butterworths.
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