The original extraterrestrial rock that fell to Earth must have been several meters in diameter, but disintegrated into small fragments of which the Hypatia stone is one.
The colourful rock that was found in western Egypt in 1996 contains micro-mineral compounds not found on Earth, in any meteorite or comet, or elsewhere in the solar system.
In the formation of the Hypatia matrix most of the polyaromatic hydrocarbons (PAH), a major component of interstellar dust, have been transformed into tiny diamonds thought to have been formed in the shock of impact with the Earth’s atmosphere or surface. These diamonds made Hypatia resistant to weathering so that it is preserved for analysis from the time it arrived on Earth.
Findings of Prof Kramers and his team at UJ
Prof Jan Kramers from the University of Johannesburg (UJ), a geochemist and expert in dating techniques and the analysis of extraterrestrial objects, describes the internal structure of the Hypatia stone as similar to a fruitcake that has fallen into some flour and cracked on impact.
“We can think of the badly mixed dough of a fruit cake representing the bulk of the Hypatia pebble, what we call two mixed ‘matrices’ in geology terms. The glacé cherries and nuts in the cake represent the mineral grains found in Hypatia ‘inclusions’. And the flour dusting the cracks of the fallen cake represent the ‘secondary materials’ we found in the fractures in Hypatia, which are from Earth.”
The Hypatia mineral matrix (represented by fruitcake dough), looks nothing like that of any known meteorites, the rocks that fall from space onto Earth every now and then.
“If it were possible to grind up the entire planet Earth to dust in a huge mortar and pestle, we would get dust with on average a similar chemical composition as chondritic meteorites,” says Kramers. “In chondritic meteorites, we 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.”
Hypatia consists of interstellar dust, which existed before our solar system was formed
“Even more unusual, the matrix contains a high amount of very specific carbon compounds, called polyaromatic hydrocarbons, or PAH, a major component of interstellar dust, which existed even before our solar system was formed. Interstellar dust is also found in comets and meteorites that have not been heated up for a prolonged period in their history,” adds Kramers.
Kramers believes the pebbles could be preserved remnants from the much larger body that impacted the Sahara and melted its sands into Libyan desert glass some 28 million years ago, though there is no way currently to test the theory.
Watch: Prof Kramers discusses his findings about the Hypatia stone.