While the hunt for prairie diamonds has slowed somewhat from mid-1990s, the search is being kept alive by
Ashton’s pursuit of diamonds at Buffalo Hills began in late 1996 when the company entered into a joint venture with Alberta Energy and
The K-14 project area is covered under a separate arrangement, with Ashton and Alberta Energy each holding a 42.7% stake, leaving Pure Gold with 14.6%. The outlying 2.44-million-ha Cayo package is held 35.6% each by Ashton and Alberta Energy, and 28.8% by Pure Gold.
Last winter, Ashton made three new discoveries on the central Buffalo Hills claim block; K252, K8, and K160, bringing to 35 the total number of bodies discovered. The company recently launched a mini-bulk sampling program to test kimberlite K252, which was discovered about 1 km northwest of kimberlite K6 and 6 km south of the K14 kimberlite complex.
Microdiamond results from K252 are among the best obtained from the 35 Alberta kimberlites discovered by Ashton, with a total of 8 macrodiamonds and 135 microdiamonds recovered from 107.1 kg of material. (A macro measures greater than 0.5 mm in at least one dimension).
The kimberlite body exhibits two distinct phases — a fine-to-medium-grained volcanoclastic kimberlite and a kimberlite breccia. A 41.6-kg sample from the volcanoclastic phase yielded 3 macros and 34 micros. One of the macros exceeded 0.5 mm in two dimensions.
A 65.5-kg sample from the breccia phase returned 5 macros and 101 micros, with three of the macros measuring greater than 0.5 mm in two dimensions. The two largest stones measured 2.35 by 2.19 by 0.63 mm, and 1.68 by 1.49 by 1.25 mm.
Kimberlite K252 is covered by 77 metres of overburden and is represented by a complex geophysical anomaly estimated to be approximately 150 metres in diameter. Ashton plans to collect a minimum 3-tonnes of kimberlite from K252 by drilling four to six core holes.
The mini-bulk sample drilling is beginning as a summer program of ground geophysics and heavy mineral sampling draws to a close. The summer work will be used to identify further drill targets for later this year or early 2001.
Results from kimberlites K8 and K160, discovered on the Buffalo Hills property last winter, are as follows: K8 liberated 4 micros and one macro from a total sample weight of 274.2 kg, while K160 gave up two micros and no macros from a total sample weight of 45.9 kg. Kimberlite K8 is covered by 38 metres of overburden and outlined by a geophysical anomaly measuring about 300 metres in diameter. Kimberlite K160 is covered by 40 metres of overburden and is delineated by a geophysical anomaly that measures about 100 metres in diameter.
Meanwhile,
The kimberlites are in the form of stacked, sub-horizontal “sill-like” zones of crater facies that have been emplaced in a sequence of Cretaceous-aged shales and sandstones. This sedimentary sequence is up to 170 metres thick and underlain by 450 metres of Cambro-Ordovician-aged dolomitic carbonate rocks. The entire package lies unconformably over metamorphic basement rocks that are interpreted to be of Proterozoic age and to form part of the Glennie Domain of the Churchill province. The property is covered by 80-125 metres of unconsolidated glacial overburden.
The most recent drill program consisted of 16 vertical holes that intersected kimberlite ranging from 5 to 128 metres. Caustic dissolution analyses, completed by Kennecott Canada’s laboratory in Thunder Bay, used a diamond recovery sieve size of 150 microns and were performed on split drill core samples with an average weight of 8 kg. Results are as follows:
Hole 3 — 6 micros and 3 macros (greater than 0.5 mm in at least one direction) from a 71.4 kg of sample.
Hole 4 — 21 micros and 6 macros from 175.9 kg of sample;
Hole 6 — 15 micros and 3 macros from 73.3 kg of sample;
Hole 7 — 29 micros and 5 macros from 174.2 kg of sample;
Hole 9 — 35 micros and 9 macros from 194.0 kg of sample;
Hole 10 — 13 micros and 4 macros from 75.3 kg of sample;
Hole 11 — 4 micros and 1 macro from 21.5 kg of sample; and
Hole 15 — 37 micros and 6 macros from 156.7 kg of sample.
A total of 160 micros and 37 macros were recovered from 942.3 kg of sample during the latest round of drilling. Five diamonds measured greater than 1.0 mm in one dimension.
The company cautions that the sample size is not yet sufficient to produce any statistically valid conclusions, however normalizing the sample weights to 100 tonnes produces a projected grade of 30 carats per 100 tonnes over several intervals. Using the same back-of-the-envelope calculations, Shore Gold reports that hole 9 has a projected grade of 35 carats per 100 tonnes for the entire hole, and 133 carats per 100 tonnes for one 31-metre interval.
The remaining holes yet to be analyzed intersected kimberlite ranging from 30 metres in hole 5, to 112 metres in hole 13. Shore plans to kick off a phase-2 drill program to further delineate the kimberlite and select the most appropriate site for a large-tonnage sample.
The Star kimberlite consists of a variety of primary, volcanoclastic crater facies covering an area of more than 2 sq. km. Thicknessess range from 150 metres in the west, tapering to about 30 metres to the northeast and south.
The kimberlite was discovered by Shore in 1996 when a magnetic anomaly measuring approximately 2.0 km by 1.5 km was drill-tested. Analysis of the core samples from three drill holes produced 179 diamonds from 465 kg of sample, which included 10 macros.
Drilling in 1997 (at one of the 1996 sites) produced 749 diamonds from 983 kg of sample, including 67 macros. The best drill hole that year yielded one diamond for every kg of sample weight, with the largest diamond recovered measuring 2.0 mm in size.
In other news,
This project is a joint venture between Kensington Resources, (38%) UEM, (10%)
Kensington has earned a 38.14% interest and funded exploration totaling $4.1 million.
The Fort a la Corne diamond cluster contains 71 kimberlite bodies. To date, 34 of the 69 kimberlite bodies tested by drilling contain macros.
The joint venture partners have selected two high priority targets, kimberlites 122 and 141, for a mini-bulk sample. The 122 kimberlite was chosen because of its immense size (it covers an area of about 108 ha), as well as its potential for commercial size stones. Geophysical modeling indicates that the 122 kimberlite may contain 540 million tonnes of kimberlite material.
The 141 kimberlite has an estimated area of 106.8 ha and an estimated volume of 395 million tonnes.
Kensington reports that a 28-person camp has been constructed and drill holes will be collared near the central part of the kimberlite bodies to maximize kimberlite intersections. The program is designed to collect up to 610 tonnes of kimberlite using a large-diameter (24-inch) reverse circulation drill. The partners expect to drill about 1,430 metres in 4 or 5 holes, depending on the thickness of kimberlite and costs of overburden drilling. About 65% of the sample will be retained for processing at the dense media separation plant operated by Monopros in Grande Prairie, Alta. Final recovery from concentrate will be performed at the De Beers facility in South Africa. The partners ultimately hope to collect 40 to 50 carats of diamonds from two kimberlites for stone valuation and to enable initial revenue modeling.
Also trying their luck in the region are
The agreement calls for Carina to issue the vendor 50,000 shares and spend $50,000 on exploration during each of the first two years. Consolidated Pine has a similar agreement, though it must issue 100,000 shares. The vendor also stands to gain additional shares when kimberlites are discovered.
The partners have completed a high resolution aeromagnetic survey over the Diamond Lady block of claims, which cover about 60,000 acres. They are contiguous to the Shore Gold property and ground held by Monopros, Kensingtion, Cameco and UEM.
In addition to the aeromagnetic survey, the partners plan to perform a detailed gravity survey on a 1,120 ha property north of the Fort a la Corne kimberlites and along the same northwest structural trend as the Snowden kimberlite cluster. They hope to drill-test targets identified by this program later this fall.
United Carina says once the geophysical results are completed, a drill program will be launched to test newly identified targets.
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