Angra dos Reis meteorite

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Angra dos Reis
TypeAchondrite
GroupAngrite
CompositionFassaite (93%)
CountryBrazil
RegionAngra dos Reis
Coordinates22°58′S 44°19′W / 22.967°S 44.317°W / -22.967; -44.317Coordinates: 22°58′S 44°19′W / 22.967°S 44.317°W / -22.967; -44.317
Observed fallYes
Fall date20 January 1869
TKW1.5 kilograms (3.3 lb)

The Angra dos Reis meteorite is the type specimen of the angrite group. It was observed when it fell to earth in 1869.[1]

Discovery and naming[edit]

The meteorite is named after Angra dos Reis, a municipality of Rio de Janeiro, Brazil. It fell on 20 January 1869 into the bay where the water was about 2 m deep. Two fragments were found by a diver the next day.[2] A category of them is named Angrito or Angrite.

History[edit]

Meteorite called Angra dos Reis is rediscovered among the debris of Museu Nacional in Rio de Janeiro. The meteorite is worth R$ 3 million and was lost in the rubble of the National Museum. With a mass 76 thousand times smaller than that of Bendegó, with mere 65 grams and 4 cm long, Angra dos Reis rock is the most valuable of the collection and was already the object of meteorite hunters, in which on 1997 was stolen, replaced by a fake stone by two north-americans, but rescued by police and researcher in Rio de Janeiro–Galeão International Airport during embarking. The Angra dos Reis takes its name because it was sighted by the doctor Joaquim Carlos Travassos, who passed in a boat in front of Praia Grande, in Angra and recovered it in the city of the coast of Rio de Janeiro in 1869. It was the first of a class of space travelers until very rare today. The object in smoke fell in the sea on the beach in front of the Church of Bonfim. Travassos ordered the slaves accompanying him to dive. Two pieces were rescued. One of them, with half a kilo, was entrusted to the Judge of Law of Angra dos Reis and, later, donated to the National Museum. From the existing reports, Travassos presented the father-in-law with the second fragment rescued from the sea, this other, bigger, with 6,175 Kg is believed to be in possession of Catholic Church since 1888. It was the first meteorite of the class of the Angritos to be discovered. There are indications that a third fragment is still at the bottom of the bay. Very rare, this class has 22 confirmed copies today. In more than a century of research, this fragment was divided into small portions. Other fractions were lost in the experiments. The biggest one was buried in the rubble of the museum, however is now safe in a plastic container, together 18 rescued, hided somewhere.[3][4] Some Meteorites were found on October 19, 2018, inclusive the Angra dos Reais, however cooked.[5] It is not known its formation. It is believed to have some 4.56 billion years during the formation of Milky Way when this was a nebula of gas and dust. The Angra was not displayed to the public, it was locked in a safe cabinet in the curator's room of the National Museum's meteorite collection, Elizabeth Zucolotto. There was a fear that, because the small dimensions, the stone would be lost in the rubble. It was Elizabeth who found it. Until, in the late 1990s, other rocks were discovered or reclassified as Angrito, a nomenclature given in reference to Angra dos Reis. According to The Meteoritical Society, there are only 28 known in the world. They are composed of minerals forged only at the very high temperatures of the planet's nucleus. They are the oldest magmatic rocks we know.

Mineralogy[edit]

Although it is the type specimen of the angrites, Angra dos Reis is actually very different from most angrites. It is almost completely made from a rare form of pyroxene called fassaite. This makes it more like a pyroxenite than the typical angrite, which is similar to a basalt. The only other meteorite samples that contain fassaite are the Calcium-aluminium-rich inclusions found in the Allende meteorite. The reason for this exotic composition is thought to be partial melting of a chondritic precursor under redox conditions in which meteoric iron is unstable.[6]

References[edit]

  1. ^ "Angra dos Reis". Meteoritical Society. Retrieved 3 January 2013.
  2. ^ "Angra dos Reis". Meteoritestudies. Retrieved 3 January 2013.
  3. ^ "Meteorito de R$ 3 milhões segue perdido nos escombros do Museu Nacional" (in Portuguese). 25 September 2018.
  4. ^ "O meteorito que vale R$ 3 milhões e está perdido nos escombros do Museu Nacional" (in Portuguese). 25 September 2018.
  5. ^ "Meteorito que vale milhões de reais é recuperado dos escombros do Museu Nacional" (in Portuguese). 25 September 2018.
  6. ^ "The Angrite Meteorite Mystery" (PDF). NASA. Archived from the original (PDF) on 2012-09-17. Retrieved 2013-01-03.