DIAMOND PAGE — Ashton sizes up K14 Alberta kimberlites

Ashton Mining of Canada (ACA-T) is encouraged by further results from bulk sampling on the K14 kimberlite complex and preliminary results from the K6 kimberlite at the Buffalo Hills project in north-central Alberta.

The Vancouver-based junior says that while the K14 complex shows a high degree of variability in diamond content, the results continue to indicate that the kimberlite contains diamonds of commercial size.

“We’re quite happy with the results,” confirms Wayne Hillier, vice-president of exploration.

The latest batch of diamonds recovered from dense media separation analysis of material from the K14 kimberlite included two stones, weighing 1.31 carats and 0.32 carat. The five largest stones previously reported weighed 0.6, 0.3, 0.28, 0.21 and 0.18 carat, representing 1.57 carats, or 32% of the carat weight recovered from the initial reverse-circulation and surface pit samples of K14A.

The latest 1.31-carat diamond is described as “a single crystal, of silver-grey appearance with many dark inclusions.” While the stone is not gem quality, Hillier says it is encouraging to see diamonds of that size come out of these small samples. The other six stones are said by Hillier to be of reasonable size and generally clear.

Ashton continues to stress that the sample size is too small to determine the quality or value of diamonds from K14 and that significantly larger-tonnage samples will be required to assess the commercial potential.

The K14 complex was first thought to be three separate pipes, but delineation drilling suggests that K14A, K14B and K14C represent a single, roughly circular, complex feature that measures about 400 metres in diameter, or 15 to 18 ha. Drilling shows a thick “apron” of tuffisitic crater facies kimberlite extending to the north and northeast of the central K14A kimberlite.

Eleven core holes were drilled into K14B and K14C areas, returning intervals of kimberlite measuring between 26 and 102 metres long. All the holes bottomed in mudstone. A 3.33-tonne mini-bulk sample of K14B, collected from four core drill holes, yielded 1.42 carats of diamonds larger than 0.8 mm in size, for a preliminary grade of 0.426 carat per tonne, or 42.6 carats per 100 tonnes.

A further 7.03 tonnes of K14B material were collected from surface pits, returning 0.51 carat of diamonds, equivalent to a grade of 0.073 carat per tonne, or 7.3 carats per 100 tonnes.

Seven holes drilled into the K14C portion yielded 0.06 carat of diamonds from a collective 2.71 tonnes of drill core material, giving a grade of 0.022 carat per tonne, or 2.2 carats per 100 tonnes.

Drilling in the central phase of K14 has confirmed kimberlite to a depth of at least 200 metres; the discovery remains open. A total of 4.38 tonnes of material collected from five core holes into the central zone returned 0.94 carat of diamonds, for a grade of 0.215 carat per tonne, or 21.5 carats per 100 tonnes.

These results compare with 8.17 tonnes of kimberlite retrieved from seven reverse-circulation drill holes, which yielded a previously reported 2.99 carats of diamonds, for a preliminary grade of 0.366 carat per tonne, or 36.6 carats per 100 tonnes. The holes were drilled vertically to an average depth of 90 metres across a 150-metre-wide section of K14A.

A further 19.2 tonnes of mini-bulk sample were collected from surface pits positioned across a 50-metre-wide section of K14A, returning a previously reported 1.87 carats of diamonds, which equates to a grade of 0.097 carat per tonne, or 9.7 carats per 100 tonnes.

Ashton has now completed analysis of all the K14 kimberlite material collected in 1997. In total, 7.79 carats of diamonds have been recovered from an aggregate 48.7-tonne mini-bulk sample of the K14 complex, for an average grade of 0.174 carat per tonne, or 17.4 carats per 100 tonnes.

Further results are pending for mini-bulk samples taken from the K5 and K6 kimberlites, though a 0.76 carat stone was recovered during the initial stages of processing of the K6 samples. The diamond is a bright yellow circular crystal, clear and transparent, with no obvious inclusions.

The Buffalo Hills project is a joint venture involving Ashton, Alberta Energy (AEC-T) and Pure Gold Minerals (PUG-T). Ashton, the operator, can earn a 42.5% interest in the original 1.4-million-acre project from Alberta Energy by spending $5 million on exploration. Pure Gold holds the right to a 15% interest.

Over the past year, Ashton has uncovered 15 kimberlite bodies on the Buffalo Hills project. The company is in the process of sitting down with its partners to plan the next stage of exploration.

The partners share ownership of an additional 4.4 million acres of surrounding ground, where exploration expenditures are shared proportionately. A further 22.5-million-acre land package is held 49% by Pure Gold, 25.5% by Ashton and 25.5% by Alberta Energy.