KIMBERLITE INDICATOR MINERAL SORTING LABORATORY

• Heavy mineral concentrates are hand sorted for kimberlite indicator minerals in Kitikmeot Geological Ltd.’s sorting laboratory in North Vancouver B.C. Experienced personnel use binocular microscopes equipped with the finest Leica optics to examine till sample concentrates for the minerals that characterize kimberlite. These minerals include purple (chromium-rich) pyrope garnets, orange eclogitic garnets, emerald green chromium diopside, olivine, enstatite, picrolimenite, chromite, and diamond. Characteristic hues, subtle surface features, and unusual shapes are used to distinguish grains that actually originated in kimberlite from similar minerals derived from unprospective rock types.
• Quality is assured by daily spiked samples provided to each sorter.
• All grains tentatively identified by sorters as kimberlite are confirmed by Kitikmeot Geological’s most experienced sorting supervisors using more advanced Leica binocular microscopes specially equipped for petrographic mineral identification. Grains of uncertain origin are mounted for chemical analysis by electron microprobe.
• Confirmed kimberlite indicator grains are counted and results entered along with all sample parameters into Kitikmeot Geological’s computer database, which is linked to sample positions by the head office.
• Pyrope garnet, chrome diopside, olivine, and ilmenite grains are further examined to classify their surface textures, quantifying the effects of abrasion and weathering. Characteristic surface textures including scratch density, fractures, etch pits and kelyphite remnants are graded using systems developed by Kitikmeot Geological based on in-house studies of different glacial dispersion trains in northern Canada. These surface texture grades provide estimates of the distance the grains have been transported from their kimberlite source.

CAUSTIC FUSION LABORATORY

• Kitikmeot Geological Ltd. operates a large-capacity caustic fusion laboratory in North Vancouver, British Columbia. The laboratory runs six 10-kg batches of kimberlite per day at full capacity, and can process 300 kg per week.
• Each batch is mixed with 100 kg of caustic soda (NaOH) in specially designed stainless steel alloy buckets, and heated to 600°C in reinforced kilns. The kiln temperature is raised in stages by a pre-programmed, computer-controlled protocol to permit maximum reduction of the sample without damage to any contained microdiamonds. The heating protocol was developed after extensive in-house experimentation using synthetic diamond spikes exposed to varied times and temperatures. Synthetic spikes included with caustic samples verify recover efficiency and the lack of any process-induced damage to natural diamonds in the sample.
• After heating in the kilns, the hot caustic soda in poured off and the residue is washed through either 120 or 200 mesh (125 or 75 micron opening) screens, depending on the objectives of each project. After washing, the caustic residue is cleaned in hydrochloric acid (HCl), and delivered to Kitikmeot Geological’s secure diamond sorting facility where it is hand-sorted under binocular microscopes equipped with reflected and transmitted light stages.
• The recovered diamonds are measured in x-y-z dimensions, and >1 mm stones are weighed in a 0.1 milligram electronic balance. The diamonds are then described using Kitikmeot Geological’s in-house grading system, and all results are entered into our computer data base, where they can be immediately accessed by geologists and planners in the head office.

HEAVY MINERAL CONCENTRATE (HMC) LABORATORY

• Kitikmeot Geological Ltd. operates a heavy mineral concentrate (HMC) laboratory in North Vancouver, B.C. with the capacity to process 50 to 100 field samples per day. The HMC laboratory is equipped with: three 24 inch automated SWECO sieving units; 6 Wilfley concentrating tables with attached hopper feeders; 1 permanent (Permaroll) and 2 adjustable (Maglift) electro-magnetic separators; 3 Franz magnetic separators; 6 Magstreams with modified collection tubes; and assorted drying racks, hot plates, and ovens. Concentrates from the laboratory are sorted for kimberlite indicator minerals, and analyzed for base metal anomalies.
• Samples are first wet sieved into -6/+10, -10/+20, -20/+40, -40/+50, and -50 mesh fractions using the SWECO sieving units, with all samples weighed and archived. For kimberlite exploration, the -20/+40 (0.850 to 0.425 mm) fraction is passed over a Wilfley table to produce the initial heavy mineral concentrate. This concentrate is then divided and reduced by magnetic separation methods to produce the smallest concentrate possible for efficient hand-sorting. Magnetic separation starts with separation of magnetic and non-magnetic fractions using the Permaroll, and production of highly magnetic and paramagnetic fractions using the Maglifts. The paramagnetic fraction is split by Magstreams on a combination of density and magnetic susceptibility into 2 concentrates, 1 containing the silicate kimberlite indicator minerals, and the other containing oxide indicator minerals. At this point the original sample has been reduced by 99.8%, and the sample is ready for hand-sorting.
• Quality is controlled by spiked samples which are run daily across the Wilfley tables and through each Magstream.
• For base metal exploration, the -50 mesh fraction is processed. This fraction is passed across the Wilfley table, to produce a heavy mineral concentrate, which is collected, dried, and weighed. The HMC is sent to an outside assaying lab for trace element analysis.
• The Kitikmeot Geological HMC laboratory uses non-toxic and environmentally safe, water based processes to produce a heavy mineral concentrate. Sieves and concentrating tables operate with only water, Permaroll and Maglift magnetic separators use no chemicals, and the Magstream uses only a non-toxic, non-carcinogenic, water soluble suspension of magnetite in ligno-sulfunate for density separation.
  
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