An elusive crystal predicted decades ago has finally been discovered trapped inside a diamond from deep Earth.  

High-pressure calcium silicate perovskite — a mineral predicted in 1967, but never before seen in nature — was found in a diamond from the lower mantle.

Researchers led from the University of Nevada used synchrotron x-ray diffraction to characterise the crystalline compound, which they have called 'davemaoite'. 

Based on their results, davemaoite has now been confirmed as a new mineral by the International Mineralogical Association. 

The choice of name honours the work of the eminent Chinese-American geophysicist Ho-Kwang 'Dave' Mao in the field of deep-mantle petrology.

The diamond with the davemaoite inclusion was formed more than 410 miles (660 km) below the Earth's surface, and was unearthed in the Orapa mine in Botswana.

'No one has ever successfully retrieved a high-pressure calcium silicate from the lower mantle before,' commented Yingwei Fei, a geophysicist from the Carnegie Institution for Science in Washington DC who was not involved in the study.

This, he explained, 'is because the high-pressure calcium silicate perovskite is "unquenchable", meaning that it cannot retain its structure after being removed from its high-pressure environment.'