Based on results from a mini-bulk sample, the K252 kimberlite is the best yet of the 35 pipes so far discovered by
A 1.3-tonne drill sample of volcaniclastic kimberlite, processed through Ashton’s dense-media-separation plant in North Vancouver, returned a 0.85-carat parcel of diamonds larger than 0.8 mm for a preliminary grade of 0.662 carat per tonne. The largest recovered stone was a colourless composite crystal weighing 0.36 carat.
The K252 kimberlite was discovered in March 2000. Two distinct phases are recognized: a fine-to-medium-grained volcaniclastic kimberlite and a kimberlite breccia. Difficult ground conditions at the contact between the two phases limited the collection of material from the breccia phase. The pipe is under 65-75 metres of overburden and represented by a complex geophysical anomaly estimated to be 150 metres in diameter.
Ashton carried out additional microdiamond testing on the two phases. An 82.6-kg sample of volcaniclastic kimberlite yielded nine macros and 84 micros (a macro is here defined as exceeding 0.5 mm in at least one dimension). The two largest stones measured 1.6 by 0.68 by 0.46 mm and 1.32 by 1.02 by 0.37 mm.
A 37.2-kg sample of breccia returned two macros and 25 micros, the largest stone being 2.45 by 1.7 by 0.45 mm.
Encouraged by the K252 results, Ashton plans to recover a larger mini-bulk sample in early 2001. K252 was identified as a drill target by an airborne electromagnetic (EM) survey and was further defined using ground EM surveys, a gravity survey and seismic data. Unlike the previous 34 kimberlites, which display a sharp magnetic contrast against the surrounding mudstone country rock, K252 is the first kimberlite discovered by the Ashton joint venture to have a weak magnetic signature.
The Buffalo Hills project is jointly held by Ashton and
In related news, a dyke-like kimberlite intrusion discovered last summer on the Ric property in Nunavut has proved diamondiferous. A 211-kg aggregate core sample from the Perseus kimberlite yielded 55 micros.
Ashton made the find after summer sampling uncovered diamonds in the till. Follow-up prospecting in the area revealed abundant kimberlite float widely distributed over a strike length of 1.4 km. An indicator mineral train and the float led to a small 400-by-600-metre lake, with an associated geophysical anomaly.
Ashton stuck five holes into the Perseus target in mid-September and determined that the kimberlite intrusive is a 10-metre-thick dyke, dipping 19 north along an east-northeast strike.
Ashton plans to drill-test Perseus in 2001 to delineate the dyke’s dimensions.
At least seven indicator mineral trains remain unexplained on the 511-sq.-km Ric property and on the 531-sq.-km Kim property, a further 25 km to the north. Exploration in 2001 will consist of further till sampling and geophysical surveys, followed by drilling if warranted.
The Ric and Kim properties are held under the Slave regional joint venture, between Ashton and
Elsewhere, Ashton has been active in the western portion of the Superior Craton, covering parts of Manitoba and Ontario, since 1993, and in northern Quebec since 1996. Ashton worked jointly with KWG and Spider Resources in 1994 and 1995, which led to the discovery of several kimberlite bodies in the James Bay Lowlands.
Ashton has since carried out reconnaissance heavy-mineral-sampling and airborne geophysical surveys, with little or no fanfare. Ashton and its partner, Quebec government-owned
One of the areas is the Otish Mountain region, 275 km northeast of Chibougamau; the other is the Caniapiscau area, 500 km east-northeast of Radisson. Both regions contained abundant indicator minerals, including some G10 pyrope garnets.
In preparation for drilling, targets will be further defined by ground geophysical surveys and till sampling in the first quarter of 2001.
Be the first to comment on "K252 deemed best pipe yet in Alberta"