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BRAZIL - SC
Iron Meteorite - Ataxite IAB.
The Santa Catarina meteorite is a nickel-rich ataxite. It is characterized by the absence of the Widmanstätten structures, which are present in octahedrites and are defined by the appearance of interlaced kamacite lamellae that follow an octahedral orientation when the surface of a metallic meteorite is attacked by nital. Meteorite Santa Catarina analyzed by the electron microprobe presented a metallic phase constituted of tetrataenite and taenite. Cracks were found in the metallic phase, filled with magnetite. Sulphide minerals such as troilite and pentlandite could be identified. Crystals of schreibersite and rhabdite were also recognized, the former as inclusions in the metallic phase, while the latter were close to troilite and pentlandite. Description obtained in the dissertation of Iara Ornellas, available on this website in Publications.
The points analyzed in the darkest part (tetrataenite) contain from 37 to 44% nickel, while the lighter part (taenite) has levels around 32% nickel. Analyzing these results, the taenite phase seems to be the most homogeneous, since there is very little variation in Ni levels. While tetrataenite was shown to be the most heterogeneous due to the variation in nickel levels. It can be seen that the results obtained by mineralogist Alexis Damour, published in Comptes Rendus, for Fe (63.69%) and Ni (33.97%), are very close to the values found for Taenite. Description obtained in the dissertation of Iara Ornellas, made available on this website in publications. Data obtained and Values obtained in Buchwald (1975): 35.3% Ni, 0.6% Co, 0.2% P, 1.8% S, 5.4 ppm Ga, 9.6 ppm Ge, 0.020 ppm Ir.
Santa Catharina is an anomalous meteorite of high terrestrial age. It is closely related to Twin City (30% Ni). It is polycrystalline with abundant troilite and schreibersite in the grain boundaries. Schreibersite, under prolonged terrestrial exposure, proved to be the most stable mineral among accessory minerals, where kamacite, taenite and troilite exhibit varying degrees of deterioration. As it did not show a Widmanstätten structure after a chemical attack, it was classified as an ataxite by the chemical IAB group . The link for entry of this meteorite in the Handbook of Iron Meteorites is http://evols.library.manoa.hawaii.edu/bitstream/handle/10524/35877/vol3-San-SantaL(LO).pdf#page=9. Source: Buchwald (1975).
Not reported by the Meteoritical Bulletin Database. It is possible to see the diverse contributions of authors throughout the century in the dissertation of Iara Ornelas (2017), available in Publications.
The Santa Catarina meteorite was discovered, in 1875, in São Francisco do Sul, probably being named as Santa Catarina, as this was a province of the Brazilian empire. This was the first of other landslides that surround this history that began with the suspicion that there would be viable iron mineral reserves in that region to be explored. The first news about the discovery of the meteorite was published in a well-known newspaper that circulated in the province of Santa Catarina, on January 23, 1875. The text was an official letter from the then president of the province - João Thomé da Silva (1842 - 1884 ) - for an engineer named Etienne Donat5, requesting that he carry out a technical evaluation on the feasibility of exploring a probable iron deposit in the region. According to Hostin (1999), Etienne Donat, who was present in São Francisco do Sul for works in the region, reported his observations on the discovery on the Island through a letter - sent with a sample of the meteorological mass - to João Thomé da Silva, emphasizing the privileged location of the find (around 3 km south of the city) and the metallic properties of the material. The president of the province of Santa Catarina needed more information about the discovery in São Francisco do Sul to inform the imperial government. The latter, then, in possession of more data, could grant or refuse the request that some inhabitants of the island made to commercially explore the probable iron reserve. In the letter addressed to João Thomé da Silva, published on January 30, 1875, the engineer mentions the names of Valetim Antonio de Souza6 and Antonio da Cunha Maciel (owner of parts of the land, where the meteorite fragments were found), who together with other inhabitants of the island, they intended to obtain an authorization from the imperial government to explore that area. Donat exposed his impressions of the site, explaining that even though he did not have the knowledge to identify iron deposits, he believed that the deposit could be a potential source of mining. I would therefore suggest that the empire take the question to a mineralogist engineer for more detailed research in order to discover whether or not there really was an iron deposit in the region. He argued that, "the mineral's richness in iron is evident and seems to promise 88 to 90%". And, because of this, exploration authorization should be granted. He emphasized the privileged position in relation to the port, talking about the ease of exporting the extracted minerals and how this discovery could revolutionize the economy of São Francisco do Sul. And why relate this news to the discovery of the meteorite? This relationship can be based on three arguments. First, the common location - São Francisco do Sul; second, the publication date of the publication - 1875; and third, those involved in the case. This third point deserves some clarification: the credit for finding this meteoritic mass, which at the time was configured as a probable iron deposit, was attributed to Manuel Gonçalves da Rosa. According to Lunay (1877, p. 84), the mineral, which was actually the meteorite, was discovered by Manoel Gonçalves da Rosa, in the Comarca of Nossa Senhora da Graça, in the province of Santa Catarina, on the southern slope of a mountain popularly known like Rocio. Fourteen fragments were found scattered around the site. Some of these pieces weighed, respectively: 2250 kilograms, 300 kilograms, 450 kilograms, 375 kilograms and 1500 kilograms. Although Manuel Gonçalves was the first to find the meteorite, his name was not mentioned in the publication, previously exposed, which dates from January 30, 1875. However, Valetim Antonio de Souza and Antônio da Cunha Maciel were among those who intended explore the area. And analyzing the imperial decree No. 6126 of February 23, 1876 that granted such authorization, it can be seen that Manuel Gonçalves da Rosa, Valetim Antonio de Souza and Antônio da Cunha Maciel were awarded the respective concession for mineral drilling of the land ( BRAZIL, 1876). The full text of this document can be viewed in “APPENDIX B” of this work. Therefore, it is concluded that the discovery of the alleged deposit of iron is, in fact, the finding of the meteorite itself. From the analysis of previous news, it can be assumed that the president of the province of Santa Catarina probably proceeded with the study of such a discovery. And the Brazilian institution that at the time had the conditions for further research was exactly the Polytechnica School in Rio de Janeiro. At the beginning of the foundation of this institution, the Brazilian empire imported some French techniques and professors, thus facilitating communication and scientific dissemination between Brazil and France. Charles Ernest Guignet (1829 - 1906) - French professor, and Gabriel Ozorio de Almeida (1854 - 1926) - student of the institution at the time (HANSEN, 2005), were responsible for the analysis of the Santa Catarina meteorite fragment. This fragment was delivered to Guignet and Ozonio by André Rebouças (1838 - 1898) - the first black engineer in Brazil. And it can be assumed that this was the sample sent by Etienne Donat to the president of the province of Santa Catarina - João Thomé da Silva - for further research. The results of Guignet and Ozorio were then published in the Comptes Rendus of 1876, producing a sequence of studies on the Santa Catarina meteorite. This discovery attracted the attention of French researchers, initiating, then, a debate on the extraterrestrial origin of the finding. It is worth remembering that the meteorite was initially named as an alleged deposit of iron, mainly due to its physical aspect, and the teachers themselves called it a “curious mineral”. Guignet and Ozorio analyzed the meteorite fragment, obtaining the proportion of 64% iron and 36% nickel, using hydrochloric acid, nitric acid and barium carbonate (MORIN, 1876, p. 917). In a later chapter, a comparative analysis of the analytical techniques of the time with the current ones regarding the study of meteorological masses will be made. Professors Guignet and Ozorio probably already suspected that the finding was a meteorite. At the beginning of the publication, they identified the fragment as a “curious mineral”, however, throughout the text, they made some notes suggestive of the extraterrestrial origin of the discovery. Did they intend to start a debate? This publication on the first analyzes of the sample was complemented with comments by the French geologist Gabriel Auguste Daubrée (1814 - 1896), who was actively involved in research and later debates. This researcher focused his discussions on the questions raised about the extraterrestrial origin of the finding, citing, for this, the appearance of the figures of Widmanstätten (DAUBRÉE, 1876, p. 918). He compared this discovery with Mr. Nordenskiöold's expedition in 1870 to Ovifak, in Greenland, which also resulted in the finding of an iron mass. He emphasized the need to analyze both situations and avoided jumping to conclusions. Ovifak's iron mass was later attributed to a terrestrial origin. And as there were similarities between them, the discussion about whether the finding in São Francisco do Sul was a meteorite or not remained active for some time. These first publications in Comptes Rendus were made in 1876 and are attributed to the results obtained by Guignet and Osorio, who worked in the laboratories of the Polytechnica School. It appears in publications from the year 1877, shown below, that samples of the meteorite were sent to the geologist Daubrée, in France, for further analysis. According to Damour (1877, p. 478), "Daubrée, having received some samples, asked me to examine them12". Mineralogist Alexis Damour (1808 - 1902) carried out studies on samples of the Santa Catarina meteorite. In his publication, he described the methodology for quantifying the following chemical elements: Fe: 63.69%; Ni: 33.97%; Co: 1.48%; S: 0.16%; C: 0.20%; Si: 0.01% and P: 0.05%. He emphasized the appearance of the figures of Widmanstätten when treating a polished surface with an acid, but he was cautious when stating: “This iron, which I assume originated from a meteorite13 [..] ‖. Therefore, it is observed through this speech that the debate to define whether the finding is of terrestrial or extraterrestrial origin was still open (DAMOUR, 1877, p. 478-481). 14 Alexis Damour's results were accompanied by an analysis by Daubrée, who explained some of his observations about the discovery: the fragment studied had a flaky structure15 similar to that seen in the Atacama siderite, which could indicate the way in which this meteoritic mass was formed; the figures of Widmanstätten were perceived after the treatment of an acid-polished surface, despite presenting very fine lines, these resembled regular geometric structures, leading the scholar to conclude that these features corresponded to “the truncation of a cube in an octahedron regular16 (DAUBRÉE, 1877, p. 483); magnetite and pyrrotite were described by the French geologist (DAUBRÉE, 1877, p. 482-485). Probably, the mineral identified as pyrrotite (Fe1-xS) was troilite (FeS), since pyrrotite is a terrestrial sulfide, while troilite is found in metallic meteorites (ZUCOLOTTO et al., 2013, p. 139). Analyzing a specific excerpt written by Daubrée, it can be seen that there was a positive expectation that the finding was really a deposit. And a mineral reserve with this large amount of nickel would attract the interest of others. The French themselves expressed their desire to control the exploitation of the alleged mine. At that point, the extraterrestrial origin of the discovery was not yet defined. The debates and discussions continued to generate more and more research. Dom Pedro II received news about the meteorite discovery in São Francisco do Sul, presenting it at the Paris Academy of Sciences. It is worth remembering that at the time of correspondence, the extraterrestrial origin of the finding was not yet defined. The report can be seen in an excerpt from a letter from Guignet to the emperor, reporting on ongoing research at the Polytechnica School. But then, when was the extraterrestrial origin of the finding defined? As explained earlier, there was a positive expectation that the discovery in the province of Santa Catarina was a small sample of an economically viable deposit with a large amount of nickel. How many possibilities could be opened, mainly with the industrial use of this chemical element? The controversy over this mass of iron and nickel was concentrated in the percentage of the latter, since at that time, minerals with such characteristics on the earth's surface were not known. It is, therefore, absolutely acceptable, that even the results obtained in the analysis of the fragments were pointing to the extraterrestrial origin, such as the appearance of the figures of Widmanstätten, the scientists were cautious in ending this discussion. However, this prudent positioning changed completely when Charles Frederick Hartt (1840 - 1878) - geologist responsible for the Scientific Commission of the Empire - visited the discovery site. This visit by Charles Hartt was described in a letter from Guignet to Daubrée. And the observations made by the naturalist were essential for ending the controversy. The fact that the rocks in the neighborhood are completely different from the meteoritic mass; and, mainly, the impossibility of finding new samples of the finding led the scientists to conclude, together with previous analyzes, that a meteorite had been discovered. As previously stated, it was not possible to find new samples at the site, which are supposed to be large blocks, as small fragments were found in later expeditions, so what was the purpose of this meteorological mass? Even though some samples were sent to the Polytechnica School and France, there are certainly many kilograms of the meteorite left. This fact will be more detailed in a later sub-item. The Polytechnica School was essential in promoting and deepening research in this case, and even in preserving history. The narrowing of scientific communication between Brazilians and the French, which occurred due to the arrival of professors from France to this institution, enabled a greater sharing of information. Regarding the meteorite, the study texts - published in Comptes Rendus - were the primary references for engineer Luiz Felipe Gonzaga de Campos20 (1856 - 1925) to undertake, in 1884, a new expedition to the Island of São Francisco do Sul. From this new venture, other fragments were found. These are currently in the National Museum of the Federal University of Rio de Janeiro; and the main mass was used in this work to carry out chemical and mineralogical analyzes. Therefore, the publication of studies in the Comptes Rendus by French and Brazilian researchers, between the years 1876 to 1878, were essential references for further research, which confirmed the extraterrestrial origin of the finding. This prevented this discovery, so important for Astronomy, from being erased from academic memory. And the creation of the Polytechnica School was indispensable in this whole process. Description obtained in the dissertation of Iara Ornellas, available on this site in Publications.
Todas as informações que não possuírem fonte especifica, foram extraídas do Meteoritical Bulletin Database.
Todas as imagens possuem direitos autorais.
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