Thursday 12 October 19.30 | £8
with Dr Mark Welch
Department of Earth Sciences, The National History, London
Diamond forms inside the Earth’s mantle at depths greater than 120 km and at temperatures above 900 ºC. At shallower depths, graphite is the stable form of carbon and is frequently encountered in sedimentary rocks. So, diamond should transform to graphite as the mantle rocks containing it rise towards the Earth’s surface by tectonic processes. However, the transformation from diamond to graphite is not instantaneous, and if diamond-bearing rocks reach the Earth’s surface rapidly the mineral can be preserved without transforming to graphite. These very unusual rocks are known as kimberlites, after the Kimberley diamond mine in South Africa.
This talk will introduce people to the extraordinary geology of diamond and how it has been used to understand the geological processes occurring at great depths inside the Earth. Rock samples containing diamond will be available to look at.
Artist/Speaker: Dr Mark Welch, Department of Earth Sciences, The Natural History Museum, London.