From the Northern Miner
The Northern Miner Volume 85 Number 39 November 22-28, 1999
DIAMOND PAGE -- Grade falls short for Tahera
Vancouver
The once-promising Contwoyto-1 kimberlite at the Jericho diamond project in Canada's newly created Nunavut territory has been
put on the back burner after further sampling by Tahera (TAH-T) determined the pipe to be of low grade.
A 50.1-tonne mini-bulk drill sample yielded 13.6 carats of diamonds for a preliminary grade of 0.27 carat per tonne. The sample was processed
at Tahera's 1-tonne-per-hour dense-media-separation plant in North Vancouver using a square screen bottom cutoff size of 1.18 mm. The
mini-bulk sample was collected from nine vertical large-diameter drill holes. Four distinct units, or phases, occur in the kimberlite, ranging in
grade from 0.15 to 0.48 carat per tonne.
Contwoyto-1 was discovered in the fall of 1998, about 38 km southeast of the Jericho JD-1 and JD-3 pipes. The discovery hole yielded 26
macrodiamonds and 143 micros from a 90.2-kg sample of kimberlite core. (A macro is defined as exceeding 0.5 mm in at least one direction.)
Preliminary estimates put the pipe in the 1.5-million-tonne range.
The Contwoyto-1 mini-bulk sample results are comparable to grade estimated for the JD-3 pipe. That pipe carries a preliminary grade of 0.36
carat per tonne based on the recovery of a 16.6-carat parcel from 46.6 tonnes of large-diameter and reverse-circulation drilling. The largest
recovered stone weighed 3.6 carats. JD-3 sits under a small lake 7 km west of JD-1 and is host to an inferred resource of 10.5 million tonnes to
a depth of 300 metres.
The Jericho project is 420 km northeast of Yellowknife, N.W.T., and 170 km north of the Ekati diamond mine. Tahera is advancing the project to
feasibility based on the construction of a small-scale diamond mining operation centred on the development of the land-based JD-1 kimberlite
pipe. SRK Consulting and DRA Mineral Plant Design Engineers are in the final stages of completing an updated prefeasibility report.
Tahera is proposing the construction of a 40-tonne-per-hour diamond recovery plant at the site of the Lupin gold mine, subject to the
implementation of the terms of a 1996 agreement between Tahera and mine owner Echo Bay Mines (eco-t). Tahera proposes seasonal
open-pit mining of JD-1 using a contractor, and trucking the kimberlite ore during the winter months along an ice road to the Lupin site, 28 km to
the southeast. The processing plant would treat the kimberlite ore on a year-round basis, producing about 300,000 carats per annum. The
tailings would be disposed of at Lupin's existing facilities. A mine life of 8-10 years is projected. Capital costs are expected to be in the
neighbourhood of $40 million.
The JD-1 pipe is estimated to host an indicated and inferred resource of 6.1 million tonnes grading 0.94 carat per tonne to a depth of 300
metres, equivalent to 5.7 million contained carats. SRK previously estimated a minable, open-pit resource of 3.8 million tonnes grading 1.01
carats per tonne to a depth of 180 metres, with a stripping ratio of 4.2-to-1. The pipe has a central higher-grade phase that contains about 2
million tonnes grading 1.42 carats per tonne.
A 9,400-tonne underground bulk sample collected across three phases of the pipe in 1996 yielded 10,539 carats of diamonds, valued at
US$59.61 per carat. The recovered stones were all larger than 1 mm and included a 40-carat stone. The largest gem-quality diamond weighed
23.89 carats. The initial evaluation excluded stones exceeding 10.8 carats. The entire parcel was revalued in 1998 at US$69.65 per carat.
Tahera's extensive land holdings cover 215,000 ha in Nunavut and are divided into four main property blocks: Jericho, Contwoyto, Burnside and
Northern. A summer field program included comprehensive mapping, extensive glacial till sampling and ground geophysical surveys over
selected areas.
At the Jericho group of claims, two priority target areas -- Jericho West and Bird Lake -- have been selected for immediate ground geophysical
follow-up during the winter 2000 exploration program. An abundance of indicator minerals is found in the two areas, which are close to the
Jericho kimberlite.
At extensive indicator mineral and kimberlite float train on the Contwoyto claims was further evaluated during the summer program. The train has
been traced over an 18-km distance in a north-southerly direction. It is up to 3 km wide in places. Selected areas are being targeted for
follow-up geophysical work in early 2000.
In a separate campaign, Rio Tinto (RTP-N) subsidiary Kennecott Canada Exploration is entering the fourth year of a joint venture with Tahera.
Kennecott can earn a half-interest in the Ice, Rocking Horse and Hood River properties by spending $50 million by 2008. The company has
spent about $14 million to date.
During the spring 1999 drilling program, Kennecott discovered the Vega kimberlite on the Ice claims and the Altair kimberlite on the Rocking
Horse property. Tahera says microdiamond analysis suggests the kimberlites are not economic. Kennecott has budgeted $2.5 million for further
exploration on the joint venture claims in 2000.
Tahera recently arranged to sell its 10-tonne-per-hour dense-media-separation test plant (housed at the Lupin mine) to Winspear Resources
(WSP-V) for $2.3 million. Grant Ewing, Tahera's vice-president of investor relations and corporate development, says the sale will bring in some
much-needed cash without any further share dilution. Tahera currently has 169 million shares outstanding, or 213 million fully diluted, and under
$1 million in cash.
Winspear intends to transport the plant by winter road to its Snap Lake project site in early 2000 to support the underground bulk-sampling
program planned for the NW dyke. |
