Twin recovers 1-carat stone from Baffin Island

Twin Mining (TWG-T) has recovered several commercial-size stones, including one weighing one carat, from test pits on the Freightrain kimberlite prospect at Baffin Island in Nunavut.

This past spring, the junior diamond explorer returned to its Jackson Inlet property to collect larger samples from two areas.

Twin was encouraged by microdiamond results from trenching last summer, when a total of 1,669 kg of fresh and weathered kimberlite material, taken from five sites, yielded 619 micros and 62 macros. (A macrodiamond is defined as exceeding 0.5 mm in at least one dimension.). The five showings occur in an area measuring roughly 360 by 100 metres.

One area, site no. 2, was trenched over a distance of 24.3 metres, from which 474 kg of kimberlite were collected in seven fresh bedrock samples at a 1.5-metre depth. In total, 130 micros and 13 macros weighing a combined 0.254 carat were recovered. The largest stone measured 2.96 mm in one dimension. A further 86 kg, collected from random sampling of weathered kimberlite fragments at surface, yielded 13 micros and three macros, including the original 0.768-carat “gem-quality” stone discovered in 1998. Kimberlite fragments are interspersed with predominant limestone fragments on frost boil surfaces.

This spring, under the supervision of senior manager Dallas Davis, Twin Mining excavated a 16.5-tonne mini-bulk sample from site no. 2, and shipped the sample to Lakefield Research for macrodiamond testing. Sampling guidelines were established by MPH Consulting, whereas MRDI Canada monitored the processing procedures.

The 16.5-tonne sample returned 74 stones in excess of 1 mm weighing 3.084 carat, for an implied grade of 0.187 carat per tonne. The largest stone recovered weighed in at 1 carat and measured 6.98 by 5.64 by 3.6 mm. It is described as gem-quality and free of inclusions. Another stone measures 3.9 by 3.19 by 2.4 mm and weighs around 0.217 carat.

The mini-bulk sample also contained a significant number of diamond fragments, reports Twin Mining, and this may indicate the breakage of other large diamonds during either the mining or processing phase. Most of the recovered diamonds are white and transparent.

A second sample was also retrieved from site no. 1, where a previous 21 kg of weathered kimberlite yielded nine micros and three macros, including one stone measuring 1.48 by 1.03 by 1 mm. A 1.91-tonne mini-bulk sample returned 12 diamonds weighing 0.56 carat, giving an implied grade of 0.293 carat per tonne. The two biggest stones weighed a combined 0.311 carat and measured 3.28 by 2.99 by 2.7 mm and 3.19 by 2.17 by 1.7 mm, respectively. Site no. 1 lies about 100 metres southeast of site no. 2.

The exposed kimberlite bedrock comprises a dark brownish green, fine-grained ground mass accounting for 20-30% of the rock. The remaining 70-80% is primarily light green olivine and of random dimensions up to 2 cm. Fragments of limestone, shale and gneiss are present. Hand specimens contain up to 10% magnetic fragments, resembling a siliceous iron-manganese shale or iron formation. These fragments are prominent in the weathered permafrost and soil material above the kimberlite body.

Lakefield Research examined thin sections of various kimberlite samples, which showed a mineral assemblage containing abundant olivine macrocrysts, with scarce phlogopite and garnet macrocrysts, set in a fine-grained matrix. The kimberlite samples exhibited a pyroclastic texture.

The Freightrain kimberlite prospect occurs on the Jackson Inlet property, 12 km from tidewater on the West Coast of the Brodeur Peninsula of Baffin Island. It lies 100 km west of the community of Arctic Bay (Ikpiarjuk), which is linked by a 21-km all-weather road to the Nanisivik zinc mine.

Prospector Fred Tatarnic first staked three mineral claims totalling 29 sq. km in August 1998 after finding a 0.768-carat diamond in weathered kimberlite. A subsequent 26.45-kg sample yielded 13 micros and two macros.

Twin entered into a preliminary agreement in April 2000 with Helix Resources, a private company associated with Tatarnic, and acquired the rights to the property for an initial payment of $50,000 and 30,000 shares. To maintain a 100% interest, Twin Mining must make further payments totalling $800,000 and 345,000 shares by the end of 2006. An additional $500,000 is due upon the receipt of development permits, and a further $1 million and 500,000 shares upon production of a half-million carats. Helix retains a 5% net profits interest and a 1% gross royalty.

Twin Mining has since staked an additional 585 sq. km of ground surrounding its Jason Inlet discovery to hold a total package of 604 sq. km. Senior Manager Davis first visited the Jackson Inlet property in May of last year and collected 94.52 kg of weathered material from a 10-by-10-metre patch bare of snow. The aggregate sample yielded 39 micros and three macros. The company then initiated trenching and sampling.

A helicopter-borne magnetometer and electromagnetic geophysical survey was flown by Fugro SIAL Airborne Surveys this spring at a line spacing of between 100 and 250 metres. Twelve magnetic anomalies were defined, including a 500-metre-diameter anomaly coinciding with the Freightrain prospect.

Nine of the anomalies occur along a 30-km-long linear trend and are spaced 2-11 km apart. The remaining three anomalies lie 20 km south of this trend. Kimberlite indicator minerals, including G10 garnets and chromite grains, were discovered at the site of magnetic anomaly no. 3, about 4.2 km east of the Freightrain prospect.

The company is set to begin an initial 2,000-metre drilling program at Jackson Inlet. Approximately 500 metres in two or three holes will test anomalies 3 and 8, whereas the remaining 1,500 metres will be directed toward the Freightrain prospect. A vertical hole will be drilled at the prospect’s centre to establish continuity, from which four other angle holes will be drilled.