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BENDEGÓ
Iron
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DESCRIPTION:
ACHONDRITE
COARSE OCTAHEDRITE
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IC
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BRAZIL - BA
1784
Iron Meteorite - IC Coarse Octahedrite.
PETROGRAPHY:
In the hand sample, at least 37 occurrences of troilite are easily identified with the naked eye on the large polished face of the main body of the meteorite exposed at the National Museum of Rio de Janeiro. They appear as dark spots, elongated and aligned in the longitudinal direction to the great axis of the meteorite. Another feature that stands out macroscopically are six coenite patches, ocher in color, with troilite nodules inside its mesh. It is also possible to observe on this polished face many kamacite lamellas forming the Widmanstätten pattern. Numerous circular or ellipsoid cavities of varying dimensions and depths are observed throughout the body of the mass, some up to 10 cm in diameter. These holes are a consequence of the ablation process during the passage of the body through the Earth's atmosphere, whose high temperature melted and vaporized the troilite (FeS) and increased the dimensions of the space previously filled by this mineral. Kamacite, an α Fe-Ni alloy, is volumetrically the predominant mineralogical phase in Bendegó, corresponding to more than 2/3 of its volume. It is presented in lamellae with an average width of 1.8 mm. In abundance, the second most important mineral in the Bendegó mass is taenite, an β Fe-Ni alloy, similar to kamacite, but with a higher Ni content. In the sample studied, taenite occurs as very thin lamellae (5 to 19 µm wide), arranged between the kamacite plates, around troilite nodules, or surrounding coenite patches. The rest of the mass is represented by a granular mixture of kamacite and taenite, in acicular form, known as plessite and numerous nodules of troilite (FeS). The set of phases present in this meteorite also includes schreibersite and rhabite (Fig. 7C), polymorphs of ((Fe, Ni) 3P), found commonly associated with coenite ((Fe, Ni, Co) 3C), chromite (FeCr2O4). Neumann lines are the result of mechanical deformations that occur at low temperatures, below 600º C (Mason 1962). In the studied sample, these lines are well defined. Carvalho et al. (2011).
GEOCHEMISTRY:
Chemical analyzes of these iron oxide fragments suggest meteoritic origin, since they contain 3.29% Nickel and 0.28% Cobalt, in addition to Iron combined with Oxygen. To see the concentrations of the other elements, access the link of the source used http://www.ppegeo.igc.usp.br/index.php/rbg/article/view/7821. Source: Carvalho et al. (2011).
CLASSIFICATION:
Bendegó is classified as a coarse Octaedrite meteorite due to its structure. Chemically, the levels found for Ni, Ga, Ge and Ir as well as the concentrations of other trace elements such as Co, W, Sb, Au and As are consistent with the IC group. When the data available for Bendegó are compared with the other members of the IC group, it is noticed that Bendegó presents intermediate levels of Ge, Au and As, and the highest value for Ga (54-56 ppm), associated with low levels Ir (0.17 to 0.22 mg / g). Source: Carvalho et al. (2011).
CLASSIFIERS:
Not reported by the Meteoritical Bulletin Database. According to Carvalho et al. (2011), several authors over the centuries have studied and reclassified Bendegó.
HISTORY:
It was discovered by the boy Domingos da Motta Botelho, in 1784. The boy was leading cattle when he realized that there was a large, brownish stone there, very different from the others in the Region. Arriving home, he commented about his discovery to his father, Mr. Joaquim. Joaquim da Motta Botelho, a faithful official of the Government, informed the authorities that he found an elevation near the Rio Vaza Barrís, in the hinterlands of Monte Santo, Bahia, “a stone of considerable size which was presumed to contain gold and silver”. The Governor at time, D. Rodrigo, was very impressed with the discovery and the following year (1785) commissioned the Captain-major of Itapicurú, Bernardo Carvalho da Cunha, to arrange his transport to the capital Salvador. Captain Cunha dug around the meteorite about 4 levels. Assisted by 30 men and a few levers, he managed to place the meteorite on a wagon specially built to transport such heavy cargo. To facilitate the passage he paved a small road to the stream. With 12 oxen joints attached to the vehicle, he set off slowly on a stone bed specially built for the cart to pass. His plan was to take the meteorite to the Bendegó stream and then to the Rio Vaza Barrís, until reaching the Port of Salvador and from there, continue by ship to the capital. Everything was going well until the streambed descent where, without brakes, the vehicle gained momentum, having its speed accelerated a lot, which imposed a friction on the axles igniting them. The cart ran wildly down the hill, ending up with the meteorite in the Bendegó stream bed, inside an ipueira tree, just 180 meters from the starting point. It was never known if any ox died in this troubled endeavor. Bernardo Carvalho da Cunha, in the face of what happened and led by discouragement, abandoned the feat. After being aware of the fact, D. Rodrigo brought him to the attention of the Minister of State of Portugal, sending him some fragments of the material. The failure, however, came to favor the fact that the meteorite is today in Brazil, because otherwise it would have ended up in Portugal or would have been totally fused in search of precious metals. The news traveled the world and the mysterious “stone” was visited by some traveling scientists, among them AF Mornay who, in 1810, who, suspecting that it was a meteorite, went to Monte Santo to find it exactly where it had been left , coming to realize that it was in fact a meteorite. With great difficulty, he managed to remove a few fragments, which, together with the personal observations collected, were sent to Wollaston, of the Royal Society of London. Six years later Mornay's letter and analyzes by Wollaston were published in the Philosophical Transactions. In his information, Mornay attributed the meteorite to a volume of 28 cubic feet and a weight of 14,000 pounds and with the dimensions of 7 feet x 4 feet x 2 feet thick. Other illustrious visitors were the pair of German naturalists Spix and Martius in 1820, who went to meet the meteorite in the company of their discoverer Domingos da Motta Botelho, already a man at that time. They found the meteorite at the same point left and still on Cap. Cunha's wagon. With great difficulty and after setting the “stone” on fire for 24 hours, they managed to remove some fragments of the meteorite, which were taken to Europe, the largest of which was donated to the Museum of Munich. As in the Sleeping Beauty story, the meteorite remained on the riverbed for about 100 years, when in 1883 Prof. Orville Derby, from the National Museum, became aware of the meteorite. Derby contacted the British Railroad engineer, who was building an extension of the road from Monte Santo to Salvador, who notified him that the road would soon reach the nearest point to the meteorite, that is, about 100 km from distance, in mountainous terrain. However, transport costs would be well above the Museum's possibilities. In 1886, Emperor D. Pedro II became aware of the fact by the Academy of Sciences of Paris, during a visit to France, offering to arrange the transport of such an important piece to Rio de Janeiro, as soon as he returned to Brazil. Here, the Emperor called Mr. José Carlos de Carvalho, a retired officer from the Paraguayan War, cousin of the English Railway engineer contacted by Derby years earlier. Informing himself of the possibilities of transportation, José Carlos de Carvalho sought support from the Brazilian Society of Geography, which took all measures to ensure that transportation was carried out. The Society took on, mainly, the financial part, obtained through a generous sponsorship of Baron de Guahy, whose baptismal name was Joaquim Elysio Pereira Marinho. Then, an Empire commission was organized for the recovery of Bendegó, formed by José Carlos de Carvalho and engineers Vicente de Carvalho Filho and Humberto Saraiva Antunes. On September 7, 1887, when the anniversary of Independence was celebrated, the work to remove the meteorite began, with a civic ceremony on the banks of the Bendegó stream. There was a landmark called “D. Pedro II ”in honor of the Emperor. On that occasion, a copy of the inauguration term for the removal work and a copy of the Bulletin of the Brazilian Geography Society, which published a memorial on the meteorite, were placed inside a small iron box. In the trip report, published in Portuguese and French in 1888, Cap. Carvalho reported in detail the transport of Bendegó, the geography of the place and the difficulties faced by all. In describing the local geography, Carvalho gave a complete view of the Region, showing the error that many wise naturalists have made who visit the sertões only in times of drought. This mistake consists in considering those places as arid deserts, without vegetation and uninhabitable. Depending on the time in which the hinterland is visited, it presents panels of a nature so different, so opposed to each other, that many times the naturalist or any other traveler finds it hard to believe that the place where he finds himself is the same he saw for a few days. or weeks before. On the occasion of the waters, which is to say of Life, the vegetation is vibrant and original, the sky is clear and the nature is enchanting. In the dry season, however, the fields are black or brown and the soil, when not sandy, cracks profoundly, the trees are bare, without foliage, except for juazeiros and umbuzeiros; and the landscape takes on an aspect of harsh winter, be it cold or temperate climates. However, it is enough that the first rains precipitate for the temperature to fall, the vegetation revives and after a few days the field turns green and flowered again, not reminding the landscape seen a few days before. The Empire Commission, after several geographical studies, chose what would be the best route for transporting the meteorite to the Jacuricy Railway Station. The path chosen was the shortest, although it had to cross the Serra do Acarú. It was also necessary to build a large part of the roads, as the existing ones were very narrow and were in a very bad state of conservation. Designed by José Carlos de Carvalho, a cart was built that could ingeniously walk on rails, or on wheels, depending on the conditions encountered on the route. The cart had two pairs of large wooden wheels, to rotate on the ground, and inside, specially calculated, metal wheels to rotate on rails, in such a way that, being on the latter, the wooden wheels did not touch the ground. Sometimes the carret was pulled by oxen joints. On other occasions, by putting the skills of a sailor into practice, he took advantage of the use of hoists, folded hoists, slates and straps and all the ingenious cable and pulley arrangements that the man of the sea knows how to use with relatively small efforts to move considerable weights. On November 25, the cart began to move over the Bendegó stream bed. On December 7, having moved for only 17 km, this primitive transport car encountered its first difficulties when crossing the Tocas River. After two days of heavy rain, the riverbed that had been dry until then was wet and slippery, causing the carrette to derail, turning and throwing the meteorite into the stream. Worked for 24 hours uninterrupted. Bonfires were lit to continue the journey the next day. The transposition of Serra do Acarú, which required an increase in ramps of 18 to 20% slope, was quite arduous. The operation was carried out by cables connected to the carret and tied to the thickest trees, purposefully left on the open road, and pulled with the help of chisels, hoists and ox joints. The report says that a tree almost gave way at the foot of the mountain. The devices burst and the caret precipitated down a 30% slope (km 22), ending happily in the middle of the slope, as the meteorite jumped in front of the caret, paralyzing it. Had it not been for this providential fall, the trailer would have been derailed to the bottom of a deep cave. Fortunately, the rains only started to fall after the passage of the Serra do Acarú. The march was interrupted seven times by the meteorite falling from the trailer and four times to replace broken axles. The commission faced several difficulties, such as the construction of steamships in lagoons, the setting up of temporary passages over the Jacuricy River of 50 meters of span, survey of embankments on flooded lowlands and the cutting of paths between slopes of stony hills. The Commission can be proud of having carried out the most remarkable transport ever made in Brazil at that time. The whole 113 km march through the Sertão, between the place where it had been abandoned 102 years before and until the Jacuricy Railway Station, took 126 days, advancing on average about 900m per day. On May 14, 1888 the meteorite arrived at the Jacuricy Station and on the 16th the arrival mark, called “Barão de Guahy”, was seated at the exact place where the meteorite embarked for the National Museum of Rio de Janeiro . A car was drawn up with all the relevant information, together with another copy of the trip and both were placed in an iron box left on the foundations of the landmark. From the Jacuricy Station, the meteorite embarked for Salvador and by train it traveled 363 km, arriving in Salvador on May 22, 1888. There it was weighed, verifying that it was then 5360 kg. The meteorite was on display in Salvador for 5 days and on June 1, it embarked on the steam “Arlindo”, going to Recife and, later, to Rio de Janeiro, where it arrived on the 15th, being received by Princess Isabel and delivered to Arsenal of Navy of the Court. At the Arsenal de Marinha workshops, a 62 kg slice was cut from which a mold was taken. The slice that was cut into several other smaller slices that were donated and exchanged with several museums in Brazil and the world. A replica of the wooden meteorite was also made, made by the Brazilian government at the Universal Exhibition of 1889. This model is now in the Museum of Natural History in Paris. On completion of the work, the meteorite was transported on November 27, 1888 to the National Museum, at that time located in Campo de Sant'Anna. Description obtained from the documents of National Museum.
All information that does not have a specific source was extracted from the Meteoritical Bulletin Database.
All images are copyrighted.
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