DIAMOND PAGE — Saskatchewan diamond exploration takes back seat to Alberta

While diamond exploration in Saskatchewan has clearly taken a back seat to Alberta’s Buffalo Hills play, a number of junior companies are forging ahead with exploration plans.

A limited drilling program was conducted in 1997 on the Fort la Corne project, 65 km east of Prince Albert. The project is 30% owned by each of Kensington Resources (KRT-V), Cameco (CCO-T) and Monopros, the Canadian exploration arm of De Beers Consolidated Mines (DBRS-Q), while German-owned Uranerz Exploration & Mining holds a 10% carried interest.

The project covers 25,488 ha of mineral claims in central Saskatchewan. Of the 69 kimberlite bodies drilled to date, 55 are confirmed to be diamondiferous, and 34 of those have yielded macrodiamonds (defined here as stones exceeding 1 mm in at least one dimension).

The 1997 program consisted of five holes totalling 1,154 metres. A single rotary hole was drilled into two previously untested targets, known as 605 and 612. A 125-metre-thick interval of kimberlite starting at a downhole depth of 109.1 metres was pulled from the 605 body, and a 57-metre-thick section of kimberlite starting at a depth of 75 metres was intersected in the 612 body. Caustic dissolution analysis of a 44.16-kg sample from the 605 body yielded nine microdiamonds with an aggregate weight of 0.001 carat. No diamonds were recovered from the 612 kimberlite.

Follow-up macrodiamond analysis of material from 605 and 612 at De Beers’ recovery facilities in South Africa came up empty.

Three large-diameter, reverse-circulation airblast holes were drilled to further evaluate kimberlite bodies 150, 176 and 220. Initial microdiamond testing of an 82-kg sample from a 159.5-metre-thick intersection of kimberlite recovered from the 150 body, starting at a downhole depth of 109.5 metres, yielded 16 stones with an aggregate weight of 0.0016 carat.

Macrodiamond analysis on a 33.5-dry-tonne, mini-bulk sample returned three macros with an aggregate weight of 0.475 carat. The sample is said to represent a theoretical mass of 59.7 tonnes, thereby giving a preliminary grade of 0.8 carat per 100 tonnes.

Microdiamond analysis of a 77.4-kg sample taken from a 170.5-metre interval of kimberlite 176, beginning at a downhole depth of 129.5 metres, yielded 22 stones with an aggregate weight of just under 0.002 carat. An additional eight macros weighing 0.775 carat were recovered from a 23.9-tonne mini-bulk sample. Based on a theoretical mass of 42.67 tonnes, a preliminary grade has been calculated at 1.8 carats per 100 tonnes.

A 84-metre-long intercept of kimberlite, starting at a depth of 102 metres, was pulled from the 220 body. Microdiamond analysis of a 78.4-kg sample revealed 159 stones with an aggregate weight of 0.039 carat, including a 1.66-mm clear yellow stone. A further 15.4 tonnes of drill sample returned 20 macros weighing 1.27 carats, including a single 0.7-carat stone described as white with abundant inclusions. Using a theoretical mass of 27.53 tonnes, the preliminary grade is 4.6 carats per 100 tonnes.

Early-stage valuations of the Fort la Corne diamonds were conducted by Antwerp, Belgium-based Luc Rombouts of Terraconsult, who looked at a parcel of 720 stones weighing a total of 37.3 carats. The average value is estimated at US$32 per carat, using year-end 1997 prices, with individual kimberlite bodies yielding stones varying from US$3 to US$89 per carat. The latter price, which was for diamonds from kimberlite body 150, is based on just 36 stones. A much larger parcel of diamonds — in the 10,000-carat range — is required to provide a definitive valuation for a kimberlite body.

The joint-venture partners are currently discussing plans for a follow-up drilling program this year.

.SCandle Lake

At the Candle Lake joint venture in the Fort la Corne area, Rio Tinto (RTP-N) subsidiary Kennecott Canada Exploration can earn a 60% interest from partners War Eagle Mining (WEM-V) and Great Western Gold (GWG-V) by incurring $8 million in exploration and development costs. Kennecott has spent $2.5 million to date.

In early February, Kennecott collected a 25-tonne mini-bulk sample from kimberlite C29/30. The sample was retrieved from two previously drilled holes, one in the thickest part of the body and the other, some 244 metres away.

Approximately 11 tonnes of the sample is currently being processed at Kennecott’s recovery plant in Yellowknife, N.W.T.

In previous drilling, C29/30 was tested with nine holes. A total of 32 macros and 149 micros were recovered from 1,345 kg of kimberlite sample. (A macro is defined here as measuring greater than 0.5 mm in any dimension.) The largest diamond recovered measured 1.2 mm.

A potential resource of 70 million tonnes is inferred for the C29/30 kimberlite body, based on results from previous drilling and geophysical data.

.SShore Gold

Saskatoon-based Shore Gold (SGF-A) completed a 5-hole drilling program in late 1996 to test four magnetic anomalies on its Fort la Corne property, 80 km east of Prince Albert. Two holes were drilled to test a circular anomaly measuring 500 metres across. The first hole hit kimberlite at a depth of 85 metres and exited the body at 330 metres, for a total intersection of 245 metres.

A 552-kg sample from the first hole yielded five diamonds, none of which met Shore’s definition of a macro (greater than 0.5 mm in any dimension).

Sampling results from the second hole have yet to be announced.

The three other holes each tested distinct anomalies within a larger magnetically anomalous area, 1.5 km west of the first target. The holes were widely spaced over an area measuring 1,300 by 600 metres. A uniform sequence of kimberlite and kimberlitic sediments was encountered in each of the holes at a depth of roughly 85 metres. A visually distinct, higher-grade kimberlite unit near the top of the sequence averages 35 metres in thickness. This unit returned seven macros and 162 micros from a combined 383.6-kg sample of the three drill holes.

An additional 81.4 kg of material, primarily taken from hole 96-3 outside of the upper zone, yielded three macros and seven micros.

Over 90% of the diamonds are described by Shore as clear and white with no inclusions. Approximately 60% of the stones exhibit crystal structure and 40% are fragments. The largest stone recovered measures 1.62 mm.

While still in the planning stage, the next phase of exploration will include a large-diameter core-drilling program. Shore Gold holds a 100% interest in over 12,545 ha in the Fort la Corne area.

.SWood Mountain

In the Wood Mountain area of south-central Saskatchewan, Pure Gold Minerals (PUG-T) and CaribGold Resources (CG-T) recently announced that a high-resolution magnetic geophysical survey over their land holdings revealed 21 circular magnetic anomalies, some of which appear to be in clusters.

Last fall, the companies jointly staked a 290,000-ha land package to cover anomalous concentrations of kimberlite indicator minerals consisting predominantly of pyrope and almandine garnets and chrome diopsides. The partners recently acquired data from a sampling program completed by the Saskatchewan Research Council in 1995 that indicates unusually high indicator mineral counts in the proximity of the magnetic anomalies.

Certain high-energy, clast-supported gravels contain common indicator mineral grains ranging from 1.74 mm to 8 mm in diameter, plus abnormally high amounts of clinopyroxene-rich sands. The unusually large size and quantity of indicator minerals indicates a nearby source.

Pure Gold and CaribGold have optioned an 80% interest in a 4,917-ha claim block surrounded by the partners’ claims. They are required to pay $7,000 and spend $500,000 on exploration over three years.