- Advanced stage diamond exploration project in Nunavut, Canada
- Large land holding, diamond interest in 1664 km2
- Located in close proximity to Rankin Inlet, and adjacent to Agnico Eagle’s Meliadine mine
- High-grade near-surface inferred diamond resource, remains open along strike and at depth
- Outstanding diamond indicator minerals in till sampling have generated multiple new exploration targets for diamondiferous kimberlite pipes
Figure 1: Dunnedin’s Kahuna Diamond Project
Kahuna is an advanced stage high grade diamond project discovered in 2001. It is located 25km from Rankin Inlet, Nunavut. Three main diamondiferous kimberlite dikes have been discovered, the Kahuna, PST and Notch. The dikes occur within an extensive network of largely untested geophysical targets, which are overlain by dense diamond indicator mineral trains.
Bulk sampling and drilling on the three main kimberlites has returned very high macrodiamond counts including diamonds over one carat in size. The largest diamond recovered was a 5.43 carat stone from the Kahuna dike that had been broken during the sample preparation process and was reconstructed as having an original size of 13.42 carats. The majority of diamonds are reported as clear and colourless to white, with a significant population of octahedral stones, however coloured stones have also been reported.
Maiden Inferred Resource Estimation
In January 2015 Dunnedin released a maiden Inferred Resource estimate from the Kahuna Diamond project, located in Nunavut, Canada. The estimate was prepared by APEX Geoscience Ltd. on the Kahuna and Notch kimberlites based on data from the 2006 – 2008 bulk sampling and drill programs completed by the past operator.
- A combined Inferred Mineral Resource of 4,018,000 carats of macrodiamonds at a 0.85 mm (+1 DTC sieve size) lower diamond cut-off, with an average grade of 1.01 carats per tonne (cpt), or 101 carats per hundred tonnes (cpht) derived from 3,987,000 tonnes of kimberlite resource.
- The kimberlites in the resource are exposed at surface and remain open to extension along strike and at depth. The average drill intercept at the Kahuna kimberlite was only 80 vertical metres, however kimberlite has been intersected at vertical depths of greater than 120 m and continuity at depth is supported by the available data.
- Indicator mineral trains and geophysics suggest the Kahuna and Notch have the potential to extend along strike into areas of thin sediment cover. Kimberlite has been intercepted in drilling along these potential extensions; however drill spacing was insufficient for inclusion in the resource. These areas will be a focus of future drilling.
- Only 2 of 8 confirmed significantly diamondiferous kimberlites (Kahuna and Notch) have sufficient drilling, bulk sampling and density definition work to be included in the inferred mineral resource at this time. Other drilled, mapped and sampled diamondiferous kimberlites include the PST, Killiq, and 4 additional kimberlite dikes located between the Notch and PST kimberlites (KD-13, 14, 16 and 18).
Drilling, surface bulk sampling, and micro- and macrodiamond data indicate the Kahuna and Notch are both single phase, macrocrystic hypabyssal kimberlite dikes having similar visual and petrographic characteristics throughout. Given their relatively simple internal geology, Kahuna and Notch were modeled as separate bodies and the Mineral Resource Estimate was established by applying average grades from surface mini-bulk samples within each geological model. Sensitivity analyses of the grades at both 0.85 and 1.18 mm cut-offs are presented in Table below:
Table 1: Inferred Mineral Resource Estimate for the Kahuna and Notch Kimberlites
|Classification||Kimberlite||Density (t/m3)||Volume (m3)||Tonnes||Average Grade cpt (+0.85 mm cut-off)||Average Grade cpt (+1.18 mm cut-off)||Total Carats (+0.85 mm cut-off)||Total Carats (+1.18 mm cut-off)|
Note: The reader is cautioned that Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability, and might never be converted into Reserves. Figures may not sum due to rounding. Decimal figures do not indicate added level of precision. cpt = (carats-per-tonne)
The potential diamond valuation or mining characteristics of the Kahuna and Notch kimberlites have not yet been determined. However, a 2008 evaluation of Kahuna diamond characteristics by Mineral Services Canada (MSC) describes the Kahuna diamond population as having encouraging value characteristics, with a high abundance of colourless and near colourless varieties with octahedral shapes being the dominant morphology. The Notch kimberlite displays similar diamond characteristics to Kahuna and other significantly diamondiferous kimberlites within the Kahuna Project including the PST and Killiq kimberlites.
The Company cautions that the inferred resource cannot be used to construct an economic model of the project prior to assembling a package of diamonds for valuation.
Dunnedin’s Field Programs
In collaboration with its technical adviser Dr. Charles Fipke and director Chad Ulansky, the company completed glacial till sampling programs collecting more than 5,000 till samples on the Kahuna property between 2015 and 2017.
Glacial till sampling recovers kimberlite indicator minerals (KIMs) and diamond indicator minerals (DIMS) that were eroded from kimberlites by glaciers and deposited down ice. This creates a train of positive till samples that can be tracked back to their original source. It is used extensively in the Canadian Arctic as a primary exploration tool leading to most major diamond discoveries, one of the most famous examples of which is Ekati. According to the results from Fipke’s lab, the Kahuna project is notable for yielding DIM chemistry associated with large diamonds.
Dunnedin’s test program utilized the same sampling and mineral ranking techniques as applied at Ekati, which can predict the potential of kimberlites to host diamonds with a high degree of confidence. The ranking employs proprietary mineral chemistry filters developed at CF Mineral Research Ltd. (CFM) under the direction of Dr. Fipke. Information on the sampling and ranking protocols is provided on this website.
In June of 2017 Dunnedin reported the identification of new kimberlite pipe targets with down-ice till chemistry matching known diamond-bearing kimberlite dikes at the Kahuna project. These are priority drill targets for that the Company believes have strong diamond potential. The drilling on these targets will take place in the winter of 2017/18.
Figure 2: Diamonds from the Kahuna Project