North Arrow recovers 268 Naujaat diamonds of +9 DTC
2022-04-26 10:29 ET - News Release
Mr. Kenneth Armstrong reports
NORTH ARROW REPORTS INITIAL BULK SAMPLE RESULTS FROM NAUJAAT DIAMOND PROJECT, NUNAVUT
North Arrow Minerals Inc. has released initial diamond recoveries from the first 70 per cent (1,316 tonnes) of a bulk sample collected in 2021 from the Q1-4 diamond deposit at the Naujaat diamond project, Nunavut. Highlights of this announcement include:
- 268 diamonds greater than +9 DTC weighing 117.98 carats were recovered from 1,316 dry tonnes of kimberlite from the A28 unit - the average size of diamonds retained on the +9 DTC sieve is ~0.21 carats;
- The three largest recovered diamonds are 3.31, 3.07 and 2.76 carats;
- 48 of the 268 diamonds (17.9 per cent) classify as fancy colour (20.9 per cent by carat weight) - indicative of a desirable and potentially high value diamond population;
- 58 per cent of the fancy diamonds classify as either "intense" or "vivid" - the two highest colour saturation classes and an important indicator of potential value in fancy colour diamonds;
- 91 per cent of the fancy diamonds classify with orange as the primary colour - orange is considered amongst the rarest colours for natural diamonds;
- +9 DTC sample grade of 9.0 cpht (carats per hundred tonnes) compares favorably with a similar sized sample collected from the same geological unit in 2014 (9.3 cpht);
- Processing of the remainder of the 2021 bulk sample, collected from the A88 unit, is ongoing.
Ken Armstrong, President and CEO of North Arrow, commented, "These initial diamond results from the 2021 bulk sample confirm the presence of an important, potentially high value, fancy orange and yellow diamond population in the Q1-4 kimberlite and add significant confidence to past results. The significant proportion of fancy colour diamonds in the sample is positive and will provide important information needed to complete ongoing modelling of the size distributions of fancy diamonds in the Q1-4 deposit and will be used in an updated average diamond price estimate in due course."
Peter Ravenscroft, Managing Director and CEO of Burgundy Diamond Mines Limited (ASX: BDM), North Arrow's partner on the project, added, "We are very pleased with the results so far of this bulk sampling program, extremely well managed by our partners at North Arrow. Initial indications are very promising, and we look forward to completion of the processing and the subsequent analysis of all results when available."
The 2021 bulk sample consists of 2,500 sample bags collected from three sample pits (Pits B, D, & E) at the multiphase Q1-4 kimberlite, located just seven kilometres from the project laydown near the Hamlet of Naujaat. The sample was divided into five subsamples for processing purposes, including four subsamples reported today: Pit B weathered kimberlite (296 bags), Pit D weathered kimberlite (445 bags), Pit B rock (325 bags) and Pit D rock (733 bags). All four subsamples are from the A28 unit of Q1-4. Processing of the fifth and final subsample, collected from the A88 unit (Pit E, 701 bags, approximately 280m southwest of Pit D), is ongoing and will be reported when received.
Mr. Armstrong continued, "Diamond recoveries reported today have been achieved using an X-Ray Transmission (XRT) optical sorter, capable of recovering diamonds larger than 2mm. The results are reported with a bottom sieve size of +9 DTC, which is the smallest sieve size for which diamonds are detected and fully recovered using the XRT. While this is a very coarse cut off for a traditional evaluation sample, it meets the needs of the current program."
A summary of the +9 DTC diamond recoveries is provided in the table below along with comparable results from the 2014 bulk sample collected from the A28 unit of Q1-4 (sample A282014).
Combined diamond recoveries from the first four 2021 subsamples include 268 diamonds greater than +9 DTC weighing 117.98 carats from 1,316 dry tonnes of kimberlite for an overall +9 DTC sample grade of 9.0 cpht. Recovered diamonds include 33 diamonds larger than the 3 grainer size class (~0.66 carat) and 21 diamonds larger than 1 carat. The three largest diamonds are 3.31 carats (Fancy intense orange irregular cube aggregate), 3.07 carats (Grey (boart) cubic aggregate), and 2.76 carats (off-white irregular octahedral aggregate).
The purpose of the 2021 sample is to acquire further information on the coarser sizes of the Q1-4 diamond population, with particular emphasis on potential high value fancy colour diamonds. As such, colour characterization studies of the diamonds have been completed using the industry standard grading scale established by the Gemological Institute of America (GIA). Forty-eight of the 268 diamonds (17.9 per cent) classify as fancy coloured (20.9 per cent by carat weight) with over 90 per cent having orange as the primary colour and 58 per cent categorized as having either intense or vivid colour saturations, the two highest colour saturations. The number of diamonds in each fancy colour grade is provided below.
The GIA colour grading scale is the industry standard for polished diamonds and, although colour grading of rough diamonds is very similar to that of polished diamonds, there is no universally accepted colour grading scheme for rough diamonds. Colour grading of the Naujaat rough diamonds provides useful information for modelling the fancy colour diamond population. However, for individual rough diamonds, the graded colour does not necessarily represent the final colour of a diamond polished from the rough stone, nor does it include characterization of a diamond's clarity (e.g. presence of inclusions or cloudiness in the diamond). Previous cutting and polishing of select Naujaat rough fancy colour diamonds has produced fancy vivid orangey yellow diamonds, certified by the GIA and demonstrating that the Q1-4 deposit can produce polished fancy colour diamonds for use in the luxury jewelry market.
The $5.6M bulk sample program is being funded by Burgundy as part of a June 1, 2020 option agreement under which Burgundy may earn a 40 per cent interest in the Naujaat Project by funding the current bulk sample program. Further details on the collection of the bulk sample can be found in North Arrow's news release dated August 19, 2021.
Diamond results reported in this release are based on dense media separation (DMS) processing, X-Ray Transmission (XRT) sensor-based diamond sorting, and diamond colour grading work completed by the Saskatchewan Research Council's Geoanalytical Laboratories Diamond Services, Saskatoon, SK (SRC), an independent diamond recovery laboratory. The sample was processed through a DMS plant configured to recover diamonds retained on a 0.85mm square mesh sieve. Kimberlite was fed directly into the DMS plant with plus 50mm oversize material first crushed to 30mm as required. All +12.5mm material was subsequently reduced through a secondary cone crushing circuit and re-introduced into the plant. Plus 0.85-12.5mm DMS concentrates were dewatered, dried, and screened into -2mm, 2-4mm, 4-8mm and +8mm fractions. Dried +2mm DMS concentrate fractions were passed through a TOMRA COM XRT 300/FR optical sorter, configured to detect and recover diamonds greater than 2mm in size. XRT accepts (concentrates) were transported to SRC's secure sorting lab for diamond sorting, cleaning, sieving and weighing in accordance with SRC handling protocols. Audits of +2mm XRT rejects (tails), using grease table and magnetic separation techniques, were completed on selected fractions. Dried +0.85-2mm DMS concentrates have been stored for future diamond recoveries, if and as required.
Quality assurance protocols, security and actual operating procedures for the processing, transport and recovery of diamonds conform to industry standard Chain of Custody provisions. As part of ongoing QA/QC programs, DMS and XRT tails, sorted XRT accepts, and other materials are subject to audit. Any significant changes in recovered diamond contents will be reported when available.