TORONTO (miningweekly.com) – Emerging diamond explorer Dunnedin Ventures has, to date, recovered 278 diamonds from a 2.4 t bulk sample collected during the 2015 field programme from the Notch kimberlite, which forms part of the Kahuna project in Nunavut.

Despite having processed only about 40% of the sample, Dunnedin noted that the diamonds were larger than the +0.425 mm sieve size, including 36 commerical-sized stones in the +0.85 mm category.

“Early results from Notch confirm an attractive diamond population with most stones being clear and colourless variants of octahedral. While we look forward to finishing this sample, we have requested that the lab immediately process till samples collected in 2015,” CEO Chris Taylor stated on Wednesday.

He added that the company would then compare indicator mineral chemistry from tills with both the PST and Notch kimberlites to guide its upcoming work. “The remaining 1.4 t of Notch kimberlite, plus additional kimberlite from PST and other targets will be processed after completion of the till samples.”

Dunnedin advised that more than 22 t of kimberlite from Notch were historically processed for diamond recovery. Commercial-sized diamond counts (+0.85 mm) were higher in the current sample than expected from historical reports; however, the current sample size was inadequate to characterise the body as a whole, and preliminary results from Notch did not constitute either a deposit grade or a completed sample grade.

The Notch sample was treated through an autogenous mill-fusion circuit located at CF Mineral Research of Kelowna, British Columbia, using a lower size cutoff of 0.425 mm.

Dunnedin’s Kahuna project was an advanced-stage high-grade diamond project located near Rankin Inlet. The project held an inferred resource of more than four-million carats of diamonds larger than 0.85 mm, at a grade of 1.01 ct/t, which had been defined along the partial strike length of the Kahuna and Notch kimberlite dykes through shallow drilling. 

The largest diamond recovered was a 5.43 ct stone from the Kahuna dyke that had been broken during the sample preparation process and was reconstructed as having an original size of 13.42 ct. Recent results included a 0.82 t sample of the PST kimberlite dyke which returned 96 macrodiamonds totalling 5.34 ct larger than 0.85 mm.