Initial caustic fusion tests on drill core from the Drybones Bay kimberlite pipe near Yellowknife, N.W.T., have so far uncovered six macrodiamonds.
The tests were carried out on 10 samples which were taken from intermittent depths within hole D95-7. The largest fragment measured 1.21 by 1.16 by 0.94 mm.
Encouraged by the results, Tradewinds Resources (VSE) is continuing its evaluation of the pipe, which now measures about 30 hectares in surface area. The program is aimed at finding a high-grade facies.
Elsewhere in the Northwest Territories
* Meanwhile, preliminary results from an airborne magnetic and electromagnetic survey over the Cook Lake joint venture in the Northwest Territories identified 25 possible kimberlite targets.
Ownership of Cook Lake is shared between Tanqueray Resources (ASE) and Mill City Gold (VSE), with 40% and 30%, respectively. The remaining 30% is split evenly between Almaden Resources (VSE) and Williams Creek Explorations (VSE).
An exploration crew is collecting samples to refine targets for drilling, to be carried out in September.
* Exploration work is also continuing on the Mackay and Back Lake properties, where partners Kennecott, SouthernEra Resources (TSE) and Kalahari Resources (VSE) are attempting to determine drill targets.
SouthernEra has spent $1.4 million on the two properties since July, 1994, and a further $750,000 will be spent this year.
To minimize costs, the joint venture will not initiate a drill program until all till samples have been processed and the data interpreted.
* Midswana Diamond Exploration, a 70%-owned subsidiary of TNK Resources (CDN), has completed drilling on its wholly owned Middlepits diamond prospect in Botswana.
The work was designed to test priority targets derived from a helicopter aeromagnetic survey in early 1995. Four targets were drilled at depths varying from 34 to 125 metres. Of the four, one encountered kimberlite, one encountered lamprophyre dykes, and two encountered quartzite.
The program was altered to test a dyke-like structure in the area of a DeBeers prospecting pit. The structure proved not to be kimberlitic, but it was found to contain dark red kimberlitic garnets at depths of between 21 and 23 metres.
All samples have been sent to a Cape Town laboratory for analysis, with results expected this summer. Midswana has retained renowned diamond exploration geologist William Jarvis to assist in the interpretation of the results of the recent exploration program.
* Preliminary results of indicator mineral and microdiamond testing on the Molopo property of Southern Africa Minerals (TSE) indicate that two additional pipes are diamondiferous.
The following data have been received on 23 of the 26 kimberlites tested on the 668,000-hectare Botswanan property:
— Eight kimberlites have returned multiple microdiamonds, with the new discovery, 94-73, containing the most (11 stones) from initial 50-kg samples; — 10 have returned G-10 (peridotitic) garnets, including five of the diamondiferous pipes above;
— four have returned eglogitic (group I) garnets, including two of the diamondiferous pipes mentioned above; and
— two of the diamondiferous kimberlites (94-73 and 94-06) are fine-grained and, although lacking in indicator minerals, are situated northeast of a 250-sq.-km area of diamondiferous river gravels. Six targets await testing in this area.
Southern Africa is considering further work on the known pipes, as well as reconnaissance testing of targets in new areas. The company has recently completed drilling at its Lekgodu property, 100 km south of Molopo, where eight kimberlites were tested. The drill is on the Kokong-Mabuasehube property, also in Botswana, where some 25 targets await testing after geophysical surveying is completed.
* Argosy Mining (VSE) has discovered its first kimberlite pipe in Tanzania, at the Mabuki reconnaissance licence. The company is in the second year of a staged, 4-year diamond exploration joint venture with Reunion Mining covering 2.9 million hectares in Tanzania and Zimbabwe.
The pipe is covered by about 4.5 metres of overburden, and the joint venture is now evaluating indicator mineral grains to determine if the structure is diamondiferous.