Encouraging diamond count on Victoria Island

Convinced De Beers walked away from Victoria Island too early, Diamonds North Resources (DDN-V) remains heartened by the microdiamond results that have started to trickle in from a slew of kimberlite discoveries it made this summer high in the Canadian Arctic.

Diamonds North drilled into three new kimberlite bodies while testing a series of geophysical magnetic features on the Nunavut side of its wholly owned Blue Ice property, 200 km northwest of Cambridge Bay. The Blue Ice property, covering 809 sq. km on Victoria Island, straddles Nunavut/Northwest Territories border.

Previously referred to as anomaly 5363, the Carina discovery has delivered modest microdiamond results. Carina was partially tested by three incomplete holes. A 23.69-kg sample of intensely clay altered, carbonate-rich kimberlite taken from the upper limits of two holes returned six micros and two macros. (A macro is here defined as measuring greater than 0.5 mm in one dimension.). Samples of a more competent, medium-to-coarse-grained, lower-phase kimberlite unit totalling 68.72 kg yielded 72 micros and six macros, including three stones exceeding 0.5 mm in two dimensions and one diamond measuring more than 1 mm in two directions.

Restating the result using the more detailed square mesh, 8-sieve-size fractions ranging from 0.1 to 1.18 mm, the two largest stones in the lower 68.72-kg sample were caught between the 0.6- and 0.85-mm sq. mesh sizes.

Diamonds North says it was unable to test the Carina kimberlite completely. The kimberlite has a magnetic signature measuring 350 metres long and a width averaging close to 125 metres. The first hole, designed to drill across the anomaly, was lost in the 32-metre-thick overburden. The next three sub-vertical holes were drilled from the middle of the anomaly, but they were cut short in kimberlite at a maximum depth of 84 metres before the holes were lost. The clay conditions proved too much for the light drill rig to handle. A full run of core was lost in the deepest hole when the rods twisted off.

The upper phase of clay-rich kimberlite, encountered between 44 and 62 metres of depth, was separated from the more competent lower phase by 8-10 metres of limestone.

The Carina kimberlite occurs about midway along a 20-km-long northwest-oriented structural corridor Diamonds North calls the “Galaxy Trend.”

The corridor is anchored by the Snow Bunting pipe at the southern end and by the Snow Goose kimberlite pipe, 6 km northwest of Carina. The Snow Bunting and Snow Goose pipes are part of the 16 kimberlites (11 pipes and five dykes) De Beers discovered on Victoria Island between 1997 and 1999. Seven of the kimberlite bodies were found on the Washburn project, optioned from Diamonds North’s predecessor Major General.

When De Beers pulled entirely out of the region in 2000, Diamonds North acquired several mineral claims covering the remaining kimberlites. De Beers retains a 1.5% gross overriding royalty and the diamond marketing rights to any commercial operation producing 1 million carats per year from these claims. Should such a milling operation be built, Diamonds North is required to pay De Beers an additional $12 million.

The exploration done to date on the property has relied heavily on magnetic survey methods, and the scope of the indicator mineral sampling has been limited. All the known kimberlite occurrences were initially detected by aeromagnetic surveys. The generally non-magnetic Paleozoic carbonate rocks, which the kimberlites have intruded, produce a benign background response. The flat-lying carbonate cover tends to mute the typically noisy magnetic response of the basement rocks, and the kimberlites that pierce the cover can stand out in contrast.

All the kimberlite occurrences except the Snowy Owl pipe have seen only a cursory amount of work, limited to one or two vertical discovery holes. These are complex kimberlites, Diamonds North President Mark Kolebaba tells The Northern Miner. “Our guess is that we have got different phases coming in, some of them have better [microdiamond] counts than others, and trying to get a handle on the stratigraphy is going to be the key.”

This summer, Diamonds North targeted the southern half or the Nunavut side of the Galaxy Trend, with grid geophysics and prospecting. While investigating selected targets, field crews turned up outcropping kimberlite and boulders in three locations within a 1.5-km distance, 3.5 km southeast of the Carina discovery. These showings, called Sculptor, Pegasus and Zeta, coincide with geophysical anomalies. Surface samples from each of the showings are being analyzed by caustic fusion methods for microdiamonds.

Starting at the southern end of the trend and systematically moving to the north, Diamonds North re-drilled the known Snow Bunting and Sand Piper kimberlites, in addition to testing several new magnetic targets. The company pulled a 20-metre-long intercept of kimberlite from Snow Bunting, which was discovered by De Beers in 1997. De Beers recovered 23 micros from a 137-kg sample, based on a 0.5-mm square-mesh screen classification. The magnetic signature of Snow Bunting is 250 metres long and 10 metres wide. The company is awaiting results.

The Sand Piper kimberlite, 1.5 km northwest of Snow Bunting, was re-tested with two angle holes. The first, collared on the northern fringe of an elongated geophysical feature 150 by 80-100 metres in size, intercepted 4.1 metres of kimberlite at a depth of 36.2-40.3 metres, followed by a second kimberlite intercept less than 1 metre thick. A 6.49-kg sample, representative of 4.1-metre kimberlite section, returned a staggering 75 micros and 43 macros weighing 0.109 carat in total. The three largest stones recovered measure 2.19 by 1.51 by 0.85 mm, 1.94 by 1.31 by 0.69 mm, and 1.82 by 1.71 by 0.89 mm.

The second hole was drilled 75 metres away, near the centre of the body, and intersected 51.4 metres of kimberlite between 42.8 and 94.2 metres. Partially reported results for the second hole include a 31.74-kg sample collected from the top 20 metres of the kimberlite intercept, which yielded 13 micros and four macros. The three largest stones were confined to a 0.3-to-0.425-mm square-mesh screen classification. Results for the lower part of the hole are pending.

Diamonds North discovered two new kimberlite bodies known as Virgo and Vega along trend of Sand Piper. The Virgo discovery is a dyke-like body, 500 metres south of Sand Piper, whereas Vega occurs as a blow 1 km to the northwest. Microdiamond results for the two bodies remain pending.

According to Kolebaba, there are quite a few undrilled high-priority targets on the Northwest Territories side of the Galaxy Trend. Based on the geophysics, they appear to be either dykes or blows.

Diamonds North has wrapped this year’s exploration program at Victoria Island. In addition to its work on Blue Ice, the company discovered five new kimberlites and re-tested two known kimberlite at the Hadley Bay joint venture with Canabrava Diamond (CNB-V). The Hadley Bay samples remain in the processing queue.

Canabrava can earn a half-interest in the Hadley Bay project by spending $5 million on exploration over four years and issuing 250,000 shares to Diamonds North, which remains as operator.

Diamonds North holds more than 5,620 sq. km on Victoria Island and has farmed out ground to Majescor Resources (MAJ-V), Serengeti Resources (SIR-V) and Hawkeye Gold International (HGO-V).

The microdiamond distribution of the two phases of the Carina kimberlite using the square mesh, sieve-size classification is shown in the accompanying table: