In an Australian crater, researchers have discovered a very rare form of zircon, a semi-precious stone generally used in jewelery. Called “reidite”, it is often associated with meteorite impacts.
Researchers at Curtin University (Australia) made a rare discovery, reported in a scientific article published in the journal Geology on September 27, 2018. Indeed, researchers found a stone called reidite in the crater of Woodleigh, located in the west of the country (Western Australia) and buried under 600 meters of rocks and sand.
Since 1997 researchers have known of the meteoritic crater, but it took twenty more years to find reidite. The latter is indeed a very rare mineral that is formed from zircon (ZrSiO4) when it is subjected to high pressures – 30 GPa (gigapascals) – and at very high temperatures. Reidite is a polymorph of zircon, which means that it has a chemical composition identical to zircon, but a different crystalline structure.
Not less than 10 times denser than zircon (5.2 g / cm3), reidite is very rarely found on Earth in its natural state. According to Aaron Cavosie, the main leader of the study, “the totality of the reidite formed in geological history would fit under a nail”. It should also be noted that this mineral was discovered after rock core samples were collected from the central ring of the Woodleigh crater.
This discovery could help scientists to better understand the mysterious phenomenon of central uplift – during the impact of the meteorite. It is also possible that the diameter of the crater is greater than 100 km, that is to say more than we thought, and this because of an underestimated impact. In the event that this value is confirmed, the Woodleigh crater will become the largest in Australia and one of the largest in the world. It would then be placed in the same category as the crater Chicxulub (Mexico), which is associated with the disappearance of dinosaurs!