More yellow diamonds found at Naujaat

North Arrow Minerals Inc. Feb. 28 reported the recovery of 64.25 carats of commercial sized (larger than 1 millimeter) diamonds from a 209.8-metric-ton mini-bulk sample collected from the Q1-4 kimberlite at the Naujaat project in Nunavut.

The three largest recovered diamonds from the sample are 5.25, 2.09 and 1.06 carats.

Yellow diamonds, representing a range of hues and tones, made up 10.7 percent of the diamonds recovered by stone count and 21.2 percent by carat weight.

With the Q1-4 kimberlite lying beneath a 0.5- to 1-meter layer of glacial till, a mini-excavator was able to collect this mini-bulk-sample last summer.

Initial evaluation of the exposed kimberlite identified a north trending internal contact between distinct kimberlite phases.

Kimberlite to the west of the contact, known as green kimberlite, accounted for roughly 30 percent of the pit area and is described as a dark green, very olivine-rich kimberlite with fine to very coarse macrocrysts (pre-dominantly olivine) and a good mantle sample.

The remainder of the pit, known as blue kimberlite, is comprised of a blue, poorly sorted olivine-rich volcaniclastic kimberlite with fine to very coarse olivine and a moderate mantle sample.

The overall sample was divided and processed separately as three subsamples – 31 bags of green kimberlite, 60 bags of blue kimberlite and 159 bags of mixed blue-green kimberlite.

The total sample averaged 0.31 carats per metric ton, with all subsamples returning similar grades, 0.25 to 0.31 carats per metric ton.

A significant population of rare, potentially high value, fancy intense to vivid orange-yellow diamonds was identified in a separate phase of kimberlite sampled during drilling of Q1-4 in 2014.

Roughly 9.9 percent of the diamonds, both by stone count and weight, recovered from the blue kimberlite subsample were yellow, which is a similar proportion as yielded in 2014.

Fewer of the potentially more valuable yellow diamonds, however, were present in the green kimberlite.

"Q1-4 requires further evaluation, in particular the collection of a larger bulk sample of sufficient size to better determine the spatial and size distributions of Q1-4's diamond population including potentially higher-value colored diamonds," said North Arrow President and CEO Ken Armstrong.

"As intended, this point source mini-bulk sample will help provide an indication of the diamond population and recoverable grade in a previously under sampled but accessible area of Q1-4 with the goal of providing information to help plan the collection of a larger bulk sample for the purposes of diamond valuation in support of an economic assessment of the deposit," he added.

–SHANE LASLEY