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Diamonds under the ice
In arctic Canada, Rio Tinto teams have mastered the toughest of environments to unearth diamonds from the roots of ancient volcanoes. Douglas Ashbury reports from a freezing frontier.

Much like the ripples around a well chosen stone tossed into a pond, diamonds from the Diavik mine in Canada's North have there own circular setting.

Carrot shaped roots of ancient volcanoes, better known as kimberlite pipes, encase Diavik's diamonds.

These ore bodies are in turn surrounded by the continent's rock core - the 2.6 billion year old Canadian Shield which arcs from Labrador around Hudson Bay to the Arctic Ocean, granite so hard that the teeth on Diavik's excavator buckets are ground down to ineffective stubs in just three days.

To open pit mine and process the prized kimberlite pipes, which are located just offshore of a 20 square kilometre island under the waters of Lac de Gras, Diavik has successfully built the first of its three planned dikes. This ring of highly engineered rockfill holds back the lake's waters and allows safe mining of the two kimberlites.

These ore bodies, a matrix of garnet, chrome diopside, olivine, spinel, chromite, ilmenite, and magnetite, have held the diamonds for 55 million years. They are the hardened magma of small ancient volcanoes which ferried the diamonds from deep within the earth to surface.



Diamonds under the ice In arctic Canada, Rio Tinto teams have mastered the toughest of environments to unearth diamonds from the roots of ancient volcanoes. Douglas Ashbury reports from a freezing frontier. Much like the ripples around a well chosen stone tossed into a pond, diamonds from the Diavik mine in Canada's North have there own circular setting. Carrot shaped roots of ancient volcanoes, better known as kimberlite pipes, encase Diavik's diamonds. These ore bodies are in turn surrounded by the continent's rock core - the 2.6 billion year old Canadian Shield which arcs from Labrador around Hudson Bay to the Arctic Ocean, granite so hard that the teeth on Diavik's excavator buckets are ground down to ineffective stubs in just three days. To open pit mine and process the prized kimberlite pipes, which are located just offshore of a 20 square kilometre island under the waters of Lac de Gras, Diavik has successfully built the first of its three planned dikes. This ring of highly engineered rockfill holds back the lake's waters and allows safe mining of the two kimberlites. These ore bodies, a matrix of garnet, chrome diopside, olivine, spinel, chromite, ilmenite, and magnetite, have held the diamonds for 55 million years. They are the hardened magma of small ancient volcanoes which ferried the diamonds from deep within the earth to surface.
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Review is published by Rio Tinto, 6 St James' Square, London SW1Y 4LD, England Telephone +44 (0)20 7930 2399 Editor: Cherry DeGeer