Deepest-forming rocks

Deepest-forming rocks
Who
Malaita deep samples
What
400–670 kilometre(s)
Where
Solomon Islands
When
19 May 2000

On 19 May 2000, geologists from the University of Queensland, Australia, announced their discovery of rocks on the island of Malaita in the Solomon Islands. These samples contained an array of minerals that only form under very high pressures, including microdiamond and majorite – a form of the mineral garnet that is rich in silica. By examining the structure of the majorite crystals, the team concluded that they had experienced pressures of up 23 gigapascals, around a quarter of a million times the atmospheric pressure at the surface. This corresponds to a depth of some 400–670 km below the surface.

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