In 2013, scientists announced that a rock fragment found in southwestern Egypt was definitely not from Earth. By 2015, other research teams had announced that the “Hypatia” stone was not part of any known type of meteorite .
However, if this piece of rock was not from Earth, what was its origin? Could the minerals in it provide clues to its origin?
Now, mineral analyzes by a research team at the University of Johannesburg have provided disturbing answers about the material from which our Solar System was formed.
To understand the structure of the Hypatia rock, named for the famous Alexandrian mathematician and philosopher, researchers have recreated the following metaphor:
“We can think of the poorly mixed dough of a fruit cake, which represents most of the fragment; what we call mixed ‘matrices’, in geological terms. The cherries and nuts in the cake represent the mineral grains found in inclusions of Hypatia. The flour that sprinkles the cracks of the cake represents the ‘secondary materials’ that we find in the fractures of Hypatia, that belong to the Earth, “he says.
The original alien rock that fell to Earth must have been at least several meters in diameter, but it disintegrated into small fragments of which Hypatia is one of them.
But the mineral matrix of Hypatia (represented by the mass of the fruit cake), is nothing like that of known meteorites , the rocks that fall from space to Earth from time to time.
“If it were possible to grind the entire planet Earth into dust in a huge mortar, we would expect to see a small amount of carbon and a good amount of silicon. But Hypatia’s matrix has a massive amount of carbon and an unusually small amount. silicon, “the researchers explain.
Fragments of the Hypatia stone, collected in southwestern Egypt in the Libyan desert./Dr. Mario di Martino. INAF, Osservatorio Astrofísico di Torino.
But what is even more unusual is that the matrix contains a large number of very specific carbon compounds , called polyaromatic hydrocarbons, a major component of interstellar dust, which existed even before our Solar System formed.
Interstellar dust is also found in comets and meteorites.
Chemical elements in unexpected ways
When researcher Georgy Belyanin analyzed the mineral grains in the inclusions in Hypatia, (represented by the nuts and cherries of a fruit cake), a number of the most surprising chemical elements appeared.
“Aluminum occurs in pure metallic form, by itself, not in a chemical compound with other elements. This occurrence is extremely rare on Earth and the rest of our Solar System, as far as it is known in science,” he explains. .
“We also found silver iodine phosphates and silicon carbide, again in unexpected forms. These grains are the first to be found as is without first having to dissolve the surrounding rock with acid,” adds Belyanin.
“In addition, there are grains of a compound consisting mainly of nickel and phosphorus, with very little iron, a mineral composition never before observed on Earth or in meteorites,” he adds.
What is the origin of Hypatia?
What the researchers do know is that Hypatia formed in a cold environment, probably at temperatures below that of liquid nitrogen on Earth (-196 degrees Celsius).
In our Solar System it would have been much further away than the asteroid belt between Mars and Jupiter, where most meteorites come from.
Comets come mainly from the Kuiper belt, beyond the orbit of Neptune and about 40 times farther from the Sun than we are.
Some come from the Oort cloud, even further afield. We know very little about the chemical compositions of the space objects are there. Our next question will delve into the origin of Hypatia, “says the study’s principal investigator, Dr. Jan Kramers.
References: Georgy A. Belyanin et al, Petrography of the carbonaceous, diamond-bearing stone “Hypatia” from southwest Egypt: A contribution to the debate on its origin, Geochimica et Cosmochimica Acta (2017). DOI: 10.1016 / j.gca.2017.12.020
