Monopros boosts grade of Hearne pipe

Partners Mountain Province Mining (MPV-T) and Camphor Ventures (CFV-V) report that the estimated value per carat of the Hearne kimberlite pipe in the Northwest Territories has increased by 48% to US$65 per carat. On a per-tonne basis, the estimated value has risen by 8% to US$111 per tonne.

The pipe is on the Kennady Lake property, which, itself, is part of the AK-CJ project, 320 km northeast of Yellowknife and 120 km southeast of Lac de Gras.

Monopros, a wholly owned subsidiary of De Beers Consolidated Mines (DBRSY-Q), can earn up to a 60% interest in the AK-CJ project by advancing it to production; for its part, Mountain Province is carried to a 36% interest, whereas Camphor is carried to 4%.

Last winter, Monopros collected bulk drill samples from a cluster of four pipes, including Hearn and three others: 5034, Tuzo and Tesla. The effort was part of a $14-million program designed to obtain enough diamonds to determine the grade and value of each pipe. Monopros will use this information to decide whether or not to proceed with a bankable feasibility study.

A 469-tonne bulk sample yielded a previously reported 846 carats for an indicated grade of 1.8 carats per tonne. The largest diamonds recovered were 3.37 and 3.16 carats. In total, 40 stones weighed more than 1 carat. Hearne was previously modeled to grade 2.33 carats per tonne at US$44 per carat. The largest diamond recovered in the 1998 test sample was 1.87 carats.

New results show an increase in the value per carat for the 1999 bulk sample: US$65, versus the US$44 estimated in the 1998 mini-bulk sample. The average grade is slightly lower: 1.71 carats per tonne, compared with 2.3 carats in the 1998 sample.

De Beers reports that 856 carats were recovered from the 469-tonne bulk sample taken from the Hearne in 1999. The systematic auditing of processed concentrates from the pipe recovered a few additional diamonds, which were incorporated into the model. Auditing of the Tuzo tailings is almost complete, and any additional diamonds discovered will be added to its grade model. Results from the Tuzo pipe are expected by late February.

Hearne consists of a northern and a southern lobe, which, in turn, have been subdivided into six phases based on the pipe’s geology. All of the pipe, except phase E of the southern lobe (between 200 and 300 metres), are classified as part of the indicated resource. Phase E is in the inferred category.

Results from the bulk sample are shown in the accompanying table.

De Beers plans to combine the recent values from the Hearne pipe with those from the 5034 pipe (T.N.M., Dec. 20-26/99), as well as the Tuzo and Tesla pipes. A decision to proceed with a feasibility study will be made once these data have been analyzed.

Meanwhile, Mountain Province has tabled results from four delineation holes completed last December. One hole was drilled northeast through the 5034-South kimberlite body towards the southwestern lobe of the 5034 pipe. It intersected 97 metres of kimberlite (67 metres projected horizontally). This extends the body by 38 metres towards the northeast.

Another delineation hole was collared on the eastern lobe of the 5034 kimberlite and drilled towards the east. The hole cut 44 metres of kimberlite (31 metres horizontally projected). It is estimated that this extension of the eastern lobe could add as much as a half a million tonnes to the previously reported 12 million tonnes of kimberlite (to a depth of 300 metres).

Another two holes were drilled into the Faraday kimberlite body, 12 km northeast of Kennady Lake. The first cut a series of narrow intersections of kimberlite about 200 metres northeast of the original discovery hole, whereas the second intersected 21 metres of kimberlite (15 metes horizontally projected) at a distance of 40 metres northeast of the original hole.

The partners say they will decide how to proceed with work on the Faraday and 5034-South kimberlite bodies once they have fully evaluated drill results and geochemical and geophysical data.

Exploration drilling on other parts of the AK claims will begin once all the till sample results from summer sampling have been analyzed.