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Highlights
Diamonds retrieved by caustic fusion of drill core from the Sequoia kimberlite show a relatively abundant presence of low nitrogen diamonds, some of which contain deep, high-pressure mineral inclusions.
Recent research globally, by academia, demonstrates that most of the world’s larger high-priced diamonds are nitrogen-free (Type II) and are deep-sourced (400 km).
This study adds to the lines of evidence that justifies acquisition of a bulk sample, large enough to give a “window” into what the run of mine would be valued at. Information required to understand the economic potential.
Research reported here, carried out at the
University of Alberta , is to be presented at the upcomingKimberlite Conference being held inYellowknife , in July.
June27th, 2024 –TheNewswire -
The diamonds recovered by caustic fusion from several drill holes were transferred to the University from the SRC laboratories in
Seventy-three (73) of these diamonds were selected for further study based on their size (>700 µm; n = 51) or the presence of visible mineral inclusions (n = 22). The diamonds were analyzed for their nitrogen content and aggregation state and for their C and N isotope compositions. Mineral inclusions from 224 diamonds were also analyzed.
Of the studied diamonds, 27% are fragments, 26% are aggregates/twins, 18% are octahedra, 18% are rounded dodecahedra/resorbed, and 11% are macles.
The colors of monocrystalline diamonds are mainly white (43%), pale yellow (48%), or brown (9%). Six of the diamonds are fibrous, highly resorbed, and black/dark grey (n = 4), white (n = 1), and yellow (n = 1) in color.
Figure 1 shows pie graphs comparing the FTIR results from this study on Sequoia diamonds to published data on diamonds from other
Figure 1: Distribution of diamond types for the Sequoia kimberlite compared to the Lac De Gras kimberlite field (Central Slave), as determined by micro-Fourier-transform infrared spectroscopy (µ-FTIR). Figure from Carvalho et al. (2024). See reference below.
Study of the mineral inclusions shows that Sequoia kimberlites tapped both lithospheric and sub-lithospheric mantle sources of diamonds beneath the Slave Craton, with peridotite being the principal diamond-bearing substrate. Five of the diamonds belong to the sub-lithospheric suite based on the presence of ferropericlase ± olivine, breyite, or larnite ± olivine, mineral associations that only form under intense pressure. The mineral inclusions were analyzed by Raman Spectroscopy. All of the diamonds classified as sub-lithospheric are either Type IaB or IIa.
For the complete parcel of Sequoia diamonds studied, the analyses have revealed that 37% of the diamonds are sub-lithospheric in source, 26% are Type IIa (no detectable nitrogen), and 11% are Type IaB. Figure 1 compares the population of stones studied from Sequoia with the published distribution of diamond types for the Lac De Gras kimberlite cluster.
Mr.
(2)Therelative lack of recovered boart material when compared with caustic fusion diamond results from other kimberlites in the Lac de Gras field. Here,only a few percent are boart,whereas on average the boart dominates at >50 percent.
(3)Theindicator mineral chemistry presented by Dr.
Due to their exceptional value, even getting one +10ct ‘special’ stone per 100,000 tonnes of kimberlite can significantly affect mine economics. Arctic plans to take a bulk sample of approximately 3000t, timed for winter 2026. Even at this size of sample, some luck would have to be involved to “see” such large stones. This size sample, limited by cost and logistics, is designed to give a good first estimate of the average value of the “run of mine” stones. If the economics from this sample prove robust on the run of mine stones alone, then every time a larger stone reports, it would be welcome bonus. The size distribution of the diamonds from the proposed bulk sample, and any variation in the quality of the stones compared from different size classes, will allow us to gain a greater understanding.
Sequoia is part of the large
The next planned step is to complete the first pass delineation of the Sequoia kimberlite complex with HQ size drilling to further understand the diamond distribution and geology. Approximately fifteen, 200m holes are planned for spring 2025. The delineation work so far (8 holes) has revealed several different kimberlite varieties, each with the potential to have different diamond populations. Completion of this work will help in the design of the bulk sample.
Of note, in a previous news release, Arctic reported a sample containing 51% Type IIa diamonds, a higher percentage than reported here. This may be due to a number of reasons. First, the original study looked at diamonds down to 0.3mm in size, and second, only looked at diamonds from the first two holes. This study looked at material from all drill holes and only stones >0.7mm. Third, the first two holes had a different mix of kimberlites to the other drill holes; there might be a kimberlite type that has an enhanced Type IIa population. This requires further work to gain understanding.
Carvalho, L.D.V., Doyle, B., Stachel, T., Pearson, G. (2024). A first look at diamonds and their inclusions from the
About
ON BEHALF OF THE BOARD OF DIRECTORS OF
“Patrick Power”
+1 (604) 218-8772
ppower@arcticstar.ca
This news release contains “forward-looking statements” including but not limited to statements with respect to the Diagras Joint Venture. Forward-looking statements, while based on management’s best estimates and assumptions, are subject to risks and uncertainties that may cause actual results to be materially different from those expressed or implied by such forward-looking statements. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements.
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