More than a decade after diamonds were first found in Canada’s Far North, new discoveries of kimberlite continue to be reported in the Northwest Territories and Nunavut.
An autumn drilling program on the Afridi Lake property of
Situated 320 km northeast of Yellowknife and 80 km southeast of the Ekati diamond mine, the 199-sq.-km Afridi Lake property is under option to
Mantle was formerly known as Intertech Minerals, prior to an 8-for-1 share consolidation earlier this year.
The junior’s involvement at Afridi Lake dates back to 1992, when it acquired an interest in the original claims. The claims remain subject to a 5% gross overriding royalty on diamonds, a 5% net smelter return royalty on other minerals, and a 10% net profits interest held by the original property vendor.
Intertech carried out regional heavy-mineral sampling and geophysics before optioning the property to Cypango Ventures in 1996. Cypango drilled a cluster of four closely spaced geophysical targets in the northwestern corner to discover the DA-1, 2 and 3 kimberlite intrusions.
The DA kimberlites are a series of narrow, steeply dipping, northwest striking dyke-like bodies. A composite 711.9-kg drill sample yielded 58 microdiamonds and eight macros weighing a total of 0.011 carat. (A macro is defined here as exceeding 0.5 mm in one dimension.). The largest diamond recovered, from the DA-3 kimberlite, was a fragment measuring 1.12 by 0.83 by 0.24 mm.
After Cypango walked, Mantle flew a comprehensive helicopter-borne magnetic and multi-frequency EM survey before entering into a deal in 1998 with Kennecott Canada Exploration, which had the right to earn a earn a 60% interest by spending $25 million on exploration over seven years. Kennecott discovered the Jordan kimberlite during a 1999 winter drilling campaign that tested six lake-based geophysical targets. Jordan was tested with two angle holes, which were drilled from the same site on the eastern end of a magnetic low anomaly, 4.5 km due west of the DA kimberlites. Collared at minus 55, the discovery hole intersected 34.2 metres of volcaniclastic kimberlite under 16.7 metres of lake bottom sediments, followed farther down-hole by a second, 14.6-metre-long intercept of hypabyssal phase kimberlite at a depth of 62.5-77.1 metres.
A 70.1-kg sample from the first hole turned out to be barren of microdiamonds, whereas a 135-kg sample from the second hole returned only two micros and two macros.
Kennecott spent a total of $1.2 million on exploration on the original Afridi Lake claims during the first six months of 1999. Branching out farther to the east, Kennecott proceeded to stake more ground, acquiring the Afridi Lake East and Alymer Lake properties. Mantle held a 40% working interest in these two properties. In the spring of 2000, Kennecott completed helicopter-borne geophysical surveys over the two properties, followed by ground geophysics on 12 targets. Two lake-based geophysical targets, one on each property, were drill-tested, but no kimberlite was hit.
In light of the results, the option agreement with Kennecott was amended and Mantle assumed operatorship of the original Afridi Lake property, while Kennecott retained a 60% back-in right.
In late 2000, Mantle drill-tested three high-priority targets in the northern half of the property, but to no avail. Mantle returned in the fall of 2001 to drill-test, unsuccessfully, two small but well-defined magnetic lows in the west-central part Afridi Lake.
During the first quarter of 2002, Kennecott agreed to terminate the Afridi Lake option agreement and relinquish its 60% back-in right. The current joint-venture arrangement with Shear Minerals, Dasher Energy and International Samuel Exploration was struck in September. The drilling campaign now under way will consist of up to 1,000 metres.
SouthernEra
This past summer,
SouthernEra can earn 60% of Yamba Lake by completing a feasibility study before the end of 2006, at which point
The Yamba Lake project generated lots of excitement and speculation in the early days of the diamond hunt, largely on the back of preliminary microdiamond counts from the Torrie pipe. The Torrie, Sue and Sputnik pipes were originally discovered in 1993 during a first pass of exploration drilling by then-partners Tanqueray, Mill City and Fibre-Klad Industries. The first two holes into the Torrie pipe returned a total of 181 micros and 53 macros from 197.8 kg of tested core.
The original discovery hole at Sue intersected 120 metres of kimberlite between a down-hole depth of 29 and 149 metres. A 97.2-kg test sample returned 12 micros and two macros. Sputnik was tested by a 50 angle hole that cut 52 metres of kimberlite over a 190-to-242-metre intercept, bottoming in kimberlite. An initial test sample weighing 23.3 kg contained three micros and one macro.
During a spring 1994 program, the partners collected a 24.5-tonne mini-bulk drill sample from Torrie, further tested the Sue and Sputnik pipes, and discovered two more kimberlites, dubbed Eddie and Ptarmigan. As part of a due diligence exercise,
In spite of the disappointing results (only 19 diamonds weighing a total 0.635 carat were recovered from the 24.5-tonne sample, for an implied grade of 2.6 carats per 100 tonnes), De Beers conducted additional geophysical surveys and infill heavy mineral sampling prior to drilling six targets. De Beers dropped its option on Yamba Lake in early 1995 after failing to turn up any additional kimberlite bodies.
Cypango later optioned Yamba Lake and re-drilled the Torrie pipe in 1997 with two holes, collecting 1.9 tonnes of sample in total. A 167.8-kg portion of the sample was analyzed for microdiamonds, using caustic fusion methods; the test returned 14 micros and four macros. The other 1,686 kg were processed by dense-media-separation to determine the potential for larger stones. Only eight diamonds weighing 0.067 carat in total were recovered, confirming the previous bulk-sampling results. On a positive note, Cypango did discover the diamondiferous T-10 kimberlite, a small multi-phase pipe in the central portion of the property.
In 1998, Cypango turned the project over to SouthernEra, which initially completed extensive airborne and ground geophysical surveys across the property and collected more than 1,000 additional till samples. Six geophysical targets were drilled resulting in the discovery of a new kimberlite dyke, known as S-141, which contained just a single micro in 40.5 kg of tested core. The Ptarmigan and T-10 pipes were re-drilled in 1999, with poor results. A 61.8-kg sample of Ptarmigan was barren of diamonds, whereas T-10 yielded two micros and one macro from 86.2 kg of kimberlite.
In 2000, SouthernEra drill-tested five geophysical targets and intercepted one kimberlite dyke. Four targets were drilled in 2001 with negative results.
The Sue kimberlite pipe has a surface expression estimated at 150 by 100 metres. The first of four holes drilled this summer by SouthernEra intersected 172 metres of kimberlite in a 45 angle hole. Based on a 0.15-mm mesh bottom screen cutoff grade, 226.7 kg of processed sample yielded 30 micros and 18 macros, including 11 stones exceeding 0.5 mm in two dimensions. The largest diamond recovered measured 1.44 by 1.1 by 1.04 mm. Microdiamond results from the three other holes are pending, as are the results from a hole that re-tested the Sputnik body.
GGL Diamond
Vancouver-based
The 251-sq.-km Seahorse property is 40 km south-southwest of Ekati and 5 km southwest off the tail end of Lac de Gras. GGL acquired the Seahorse property in 2000, along with the Mackay and Courageous properties, by staking, as old mineral claims lapsed. GGL continued to stake new ground in 2001 and 2002.
The Seahorse claims were part of a larger area previously explored by Kennecott and De Beers, and subsequently dropped. The area previously saw 250-metre-line spaced Geoterrex airborne geophysical surveys, 150-metre-line spacing Dighem airborne surveys, and till sampling.
Based on the premise that the previous work was too wide for the region’s potential to be properly assessed, GGL began a program of regional reconnaissance. The junior took 238 till samples and 229 soil samples in 2000-2001 while completing 3,600 line km of airborne geophysics, followed by a seismic survey and ground surveys over nine targets. One target was drilled at Seahorse without intersecting kimberlite. The till samples yielded 408 indicator mineral grains consisting of garnet, chrome diopside, olivine and ilmenite. Concentrations ranged up to 11 indicator grains per sample.
This summer, GGL returned to the Seahorse and Starfish claim areas and collected a further 455 tills and 550 soil samples before beginning a drilling program consisting of three holes. The first round of drilling was laid out to test three conspicuous magnetic anomalies at Seahorse. However, the anomalies are not supported by indicator mineral dispersion trains.
Angled at minus 45 and drilled to a down-hole depth of 226 metres, the first hole intersected multiple intervals of kimberlite totalling 83.3 metres in length. The kimberlite sections, at 88.5-119 metres, 120.6-134.5 metres and 138.8-177.7 metres, are interspersed in metasedimentary rocks.
The second angle hole, drilled 670 metres to the south-southeast, hit two sections of kimberlite totalling 56.4 metres at 38.5-70.47 metres and 92-116.4 metres down-hole. The hole ended in metasediments at a depth of 200 metres.
The final hole stepped out on a third target a further 350 metres to the southeast and cut three intervals of kimberlite, combining for 40.17 metres in total. The kimberlite sections run from 113.5 to 147 metres, from 151.2 to 157.7 metres and from 222 to 222.17 metres down-hole. The hole continued in metasediments to a depth of 275 metres.
GGL intends to raise $2 million by way of a private placement of 10 million shares priced at 20 apiece. The junior has 52.7 million shares outstanding.
Archon
A year ago,
After a false start last spring, Archon returned to the WO block in August to begin testing some 19 geophysical pipe-like targets identified by BHP. The WO claim block lies directly south of the Diavik diamond mine project. BHP flew the property last fall with its Falcon survey.
While drilling a lake-covered gravity low (the fourth target to be tested), Archon intercepted 38.7 metres of crater facies kimberlite in a minus 47 angle hole drilled from the shoreline. The discovery hole was shut down while still in kimberlite at a down-hole depth of 87 metres. The surface expression of the gravity low is 3.1 hectares.
Kennecott previously discovered eight kimberlites on the WO claims, including the infamous Tli Kwi Cho (DO-27 and DO-18) diamondiferous pipes. The new kimberlite discovery is 2.1 km southwest of Tli Kwi Cho and just 200 metres north of the DO-29 kimberlite body. DO-29 is described as a “multi-phase system, which includes hypabyssal kimberlite dykes, pyroclastic (crater facies) kimberlite and heterolithic kimberlite breccias.” Kennecott previously tested DO-29 with two holes in 1993 and one hole in 1998. An 82.7-kg sample of kimberlite from the 1998 hole yielded 12 micros. Results are not known for the 1993 holes.
The WO claims are held 55% by DHK Diamonds, 20% by Archon, 15% by
BHP can earn a 54.5% stake in the WO block by electing to bulk-sample at least 200 tonnes from any kimberlite discovered as a result of the Falcon survey. The BHP option excludes the nine known kimberlites.
A sister company of Kettle River,
Diamondex
Elsewhere in the region, Randy Turner’s
Farther afield,
During a spring drilling campaign, Kennecott tested 20 exploration targets at Jericho without intersecting any kimberlite.
The Jericho properties lie along the northwestern and northeastern shores of Contwoyto Lake, 26 km north of the Lupin gold mine, and 420 km northeast of Yellowknife. Six kimberlites have been found on the Jericho properties to date.
The proposed Jericho mine project centres on the land-based Jericho multi-phase pipe, which contains a total resource of 7.1 million tonnes grading 0.84 carat per tonne, equivalent to 5.9 million carats. A June 2000 feasibility study by SRK Consulting concluded that a combined open-pit and underground mining operation could produce an estimated 3 million carats over a life of eight years, based on a probable minable reserve of 2.5 million tonnes grading 1.19 carats per tonne. A re-evaluation of the diamonds by WWW International Diamond Consultants in early 2000 indicated a value range of US$75-88 per carat.
Capital costs for the open-pit operation are estimated at $44.5 million, plus a further $10.4 million for underground and sustaining costs. Operating costs over the life of mine are projected at $52 per carat. Tahera continues to evaluate the benefits of developing the project through a co-operative arrangement with one of several groups that have expressed an interest in financing the project.
As part of its obligations for entering into an option on the Jericho project, Kennecott completed a $1-million private placement in Tahera in early October by subscribing for 6 million shares priced at 16.7.
At the Rockinghorse joint venture in the Coronation Gulf district, 120 km northwest of Jericho, where Kennecott discovered the highly diamondiferous Anuri kimberlites, there are no details available regarding the next stage of evaluation.
Kennecott spent the spring delineating the twin Anuri bodies with four core holes, in addition to testing upwards of a dozen new targets with limited success. A new kimberlite, Atani, was discovered 16 km north of the Anuri kimberlites. A 120-kg test sample yielded just four micros.
The Anuri and Anuri East kimberlites are believed to coalesce in the upper region. The Anuri kimberlite has a surface expression measuring 225 by 150 metres, whereas Anuri East is 100 by 100 metres. The kimberlites have been tested to a depth of over 200 metres.
In total, 1,496 kg of tested core from the Anuri and Anuri East kimberlites returned 1,098 micros and 552 macros, including 110 stones exceeding a 0.5-mm square mesh screen size and 14 diamonds larger than 1 mm square mesh. The largest diamond recovered weighed three-quarters of a carat.
During the summer, Kennecott collected an additional 75 till samples to define anomalous areas, while drill-testing two gravity targets with no success. Kennecott, a division of
Rhonda
In the heart of the Coronation District,
Elsewhere in the Coronation area, the Northair Group’s
Summer exploration work on the Coronation properties focused on till sampling, prospecting and ground-checking geophysical anomalies identified from more than 31,000-line km of airborne surveys flown during spring 2002. About 1,850 samples were taken from the jointly held properties.
In addition, a summer field program at the Aviat properties on the Melville Peninsula of Baffin Island focused on sampling and prospecting. More than 300 samples were collected and a potentially kimberlitic dyke-like body was identified.
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