In the new study, the scientists examined two pieces of glass from the Al-Jawf area in southeastern Libya. They were studied using a state-of-the-art transmission electron microscopy technique. They found small minerals, different types of zirconium oxide, in the glass. The minerals are made up of chemical elements whose atoms form a regular three-dimensional packing. One of these modifications is called cubic zirconium, it is found in some jewellery as a synthetic replacement for diamonds. This mineral can only be formed at high temperatures between 2,250 and 2,700 degrees Celsius.
In addition, scientists have discovered a very rare polymorph ortho-II, which is formed only at very high pressure – about 130,000 atmospheres. Having compared the parameters of pressure and temperature required for the formation of these polymorphs, the authors of the study came to the conclusion that the glass could be formed only in the impact of a meteorite or the explosion of an atomic bomb. Given the age of the samples, they settled on the meteorite theory.
