Australia’s Lucapa Diamond has hit a major milestone at its prolific Lulo mine in Angola, after recovering 20 diamonds weighing a combined 15.51 carats from just one bulk sample.
The company said that the diamonds had been recovered from the initial processing of around 20% of the kimberlite bulk sample.
Five diamonds are greater than one carat, with the largest weighing 1.95 carats. This represents a preliminary grade of roughly 2.5 carats per one hundred cubic metre from the processing of kimberlite material, it said.
While processing of the kimberlite bulk sample is in progress, Lucapa said the recoveries so far already are the highest count and carat weight of diamonds recovered from any kimberlite bulk sample processed at Lulo.
“This preliminary result represents the best kimberlite diamond recoveries to date, confirms the existence of higher grade primary sources with commercial size diamonds and it bolsters our large geological database,” managing director Stephen Wetherall noted.
“We are beginning to see the desired outcome of the methodical exploration approach in a significant diamond province which has been accelerated by the recent commissioning of the dedicated bulk sample plant,” Wetherall.
Lucapa has a 40% stake in the Lulo mine, which hosts the world’s highest dollar-per-carat alluvial diamonds. The rest is held by Angola’s national diamond company (Endiama) and Rosas & Petalas, a private entity.
This year alone, the partners have recovered 28 stones exceeding 100 carats, with the Lulo Rose, found in September, taking the fifth place among the largest rocks dug up at the mine regardless of its colour.
The mine, which began commercial production in 2015, yielded the largest ever diamond recovered in Angola — a 404-carat white stone later named the “4th February Stone”, in 2016.