LAC DE GRAS – North of Yellowknife, NWT.
- Type: Man Made Structure
- Location:N 64° 31′ W 110° 34
|Geology of Lac de Gras
The Diavik Diamond Mine ore reserve comprises three diamond-bearing kimberlite pipes that are currently been mined using open pit mining methods. All three kimberlites will eventually also be mined from underground. 55 million years ago, volcanic activity injected kimberlite magma towards the surface, bringing with it diamond bearing ore and forming the kimberlite pipes which are today mined for its precious ore.
The Diavik Diamond Mine is located in one of the most remote and forbidding places in the world – 220 kilometres south of the Arctic Circle and on the bed of a vast northern lake, Lac de Gras. A single road, built out of ice and crossing frozen lakes, connects the mine with other operations and Yellowknife, capital of the Canada’s Northwest Territories. The construction of open pit and underground mining operations and related infrastructure are engineering feats on a grand scale. Open-pit mine construction included the building of rockfill dikes to hold the frigid waters of Lac de Gras at bay. Not only did the extremely harsh climatic conditions present significant construction challenges, but nothing was allowed to blemish the pristine waters of the lake during its building.
Diamonds were first discovered in the Lac de Gras region in the early 1990s, and construction of the Diavik Diamond Mine completed in 2003. The mine, which has a current footprint of approximately 10 square kilometres, is projected to produce well over 100 million carats of diamonds over its mine life of 16 to 22 years.
Diavik currently mines three diamond-bearing ore bodies known as kimberlite pipes. The pipes are called A154 South, A154 North and A418. Open pit mining of the three pipes has now concluded and Diavik completed its transition to an all underground mine in September 2012. Mining and processing of initial ore from Diavik’s new underground mine commenced in early 2010.
At 31 December 2012, Diavik had ore reserves of 18.3 million tonnes at 2.9 carats per tonne.