Lac de Gras a wide and long stream called the Narrows. The median flood peak discharge in the Narrows is making it an important corridor for fish movements. Lac de Gras Lac de Gras is a lake approximately north east of Yellowknife, in the Northwest Territories of Canada. Lac de Gras was the centre of the diamond rush of the 1990s. There are two working, and one closed, diamond mines in the area, Diavik Diamond Mine, Ekati Diamond Mine, and the care and maintenance Snap Lake Diamond Mine. It was called Ekati by aboriginal peoples. The lake is ultraoligotrophic but supports a slow-growing
Williamson diamond mine about 1,100 staff, mostly Tanzanians. The mine is located about south of the town of Mwanza in Kishapu District of Shinyanga Region. Dr. Williamson, the discoverer of the site, first owner and namesake of the mine, named the site "Mwadui" after a local chief; "Williamson" and "Mwadui" are now virtually synonymous in the diamond mining world. The most important geological feature of the Williamson diamond mine is the kimberlite pipe on which it is located. At 146 square kilometers in area at surface level, it ranks as the largest economically exploitable diamond-bearing volcanic pipe in the world. Recent exploratory drill