A rare form of ice has been found inside diamonds that were newly unearthed around the world, according to a study published in Thursday's Science journal.
The type of ice, known as ice-VII, features a cubic shape and is about 1.5 times as dense as the regular ice -- ice I.
Different from other solids, whose atoms squeeze together under higher forms of pressure, water-based ice rearrange themselves into new structures when subjected to increasing pressure.
For example, if you press down hard enough on ice-I, it will transform into ice-II, which has a rhombohedral structure. Increase the pressure once gain and the atoms will rearrange themselves into ice-III, then IV, V, VI and VII.
Once it reaches the phase of ice-VII, the structure remains fairly stable even as the pressure increases.
The discovery has cheered the scientists, who previously believed that ice-VII only existed on other planets of the solar systems.
"Water in diamonds is not unknown, but finding this very high pressure form of water ice intact, that was really fortuitous," George Rossman, a mineralogist at Caltech, told the Los Angeles Times. "That's what you call discovery."
Thanks to their discovery, ice-VII has been recognized for the first time as a mineral in the International Mineralogical Assn.
Those diamonds with ice-VII inside were collected from mines in Africa and China.