TORONTO (miningweekly.com) – The world’s largest diamond producer by volume, Russia’s Alrosa, has recovered a 241.21 ct rough diamond from the Nyurbinskaya pipe.
It is one of the largest rough diamonds recovered in the Russian Federation and the third-largest among those found at the Nyurba mining and processing division, the company advised Thursday.
The carbon crystal measured 38.64 mm by 27.34 mm by 25.46 mm, and was translucent with a grey hue. Traces of dissolution-etching channels and caverns were observed on the surface. The intermediate and peripheral zones contained large cracks, one of which was ferruginised. The crystal contained graphite and sulphide inclusions.
Alrosa said the diamond was designated a colour of 4 Black Clivage/Makeable 2.
After discovery in 1996, the Nyurbinsky openpit mine was put into operation in 2001. As of January 1, 2015, the kimberlite pipe contained Joint Ore Reserves Committee-compliant reserves totalling 36.9-million carats.
The Nyurba mining and processing division was one of Alrosa’s youngest enterprises, operating the Nakyn ore field containing the Nyurbinsky and Botuobinsky openpit mines, and two eponymous alluvial placer operations. The division accounted for about 20% of the miner’s output in 2015, the company advised.