In 2013, scientists announced that a fragment of rock found in southwestern Egypt was definitely not from Earth. By 2015, other research teams had announced that the “Hipatia” 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, the mineral analyzes conducted 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 after a famous Alexandrian philosopher and mathematician, researchers have recreated the following metaphor:
“We can think of the badly mixed mass of a fruit cake, which represents most of the fragment, what we call mixed ‘matrices’, in geological terms.Cherries and nuts in the pie represent the mineral grains that are found in inclusions of Hypatia The flour that sprinkles the cracks in the cake represents the ‘secondary materials’ that we find in the Hypatia fractures, which belong to the Earth, “he says.
The original extraterrestrial 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 fruitcake), does not look anything like the known meteorites, rocks that fall from space to Earth from time to time.
“If it were possible to grind the entire planet Earth so that it would turn 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 of silicon,“explain the researchers.
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 was formed.
The interstellar dust also in comets and meteorites.
Chemical elements in unexpected ways
When the researcher Georgy Belyanin analyzed the mineral grains in the inclusions in Hypatia (represented by the nuts and cherries of a fruit cake), a quantity of the most surprising chemical elements appeared.
“Aluminum is presented 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, so it is known in science”, explains .
“We also find silver iodine phosphates and silicon carbide, again in unexpected ways, these grains are the first to be found as they are without first having to dissolve the surrounding rock with acid,” adds Belyanin.
“In addition, there are grains of a compound that consists 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 was formed in a cold environment, probably at temperatures lower than that of liquid nitrogen on Earth (-196 degrees Celsius).
Comets come mainly from the Kuiper belt, beyond the orbit of Neptune and some 40 times farther from the Sun than we are.
Some come from the Oort cloud, even further away. We know very little about the chemical compositions of space objects are there. Our next question will delve into the origin of Hypatia, “says the study’s principal investigator, Dr. Jan Kramers.