Beginning in late 2003, extensive drilling works were undertaken on the AK6 Kimberlite. The drilling can be divided into that done to delineate the extent of the Kimberlite and to map its internal geology, and density, and that done to obtain large Kimberlite samples for diamond grade and revenue estimation. The drilling is summarized in the table below, grouped into the exploration phases:
Summary of exploration drilling programmes on the AK6 Kimberlite
|Phase of Programme||Purpose of Drilling||Drill Type||Hole size||No. Holes||Total Meters||Duration|
|Initial Exploration||Initial sampling||Percussion (reverse circulation)||12 ¼"||5||679||Late 2003-2/2004|
|Advanced Exploration Program Phase 1||Delineation||Percussion||6 ½"||44||4,575||2004-2005|
|Advanced Exploration Program Phase 2||Piloting||Core||NQ||11||4,181||11/2005-08/2006|
The work summarized in the above table totals 22,743m of core drilling and 7,964m of Large Diameter Drilling ("LDD"), plus the initial 12¼" reverse circulation work and 6½" delineation drilling. The hole size refers to size at completion; starting size was generally larger. The LDD method used was the reverse flood airlift assist system.
Phase 1 pilot drilling was sub-contracted to R A Longstaff (Pty) Ltd of Selebi-Phikwe, but their services were discontinued after Phase 1. All prior and subsequent drilling was contracted to De Wet Drilling (Pty) Ltd of Rasesa, Botswana.
Drilling methods and details of the drilling undertaken for the Phases set out in the above table are described in detail in the AK6 Kimberlite Technical Report.
The AK6 Kimberlite has been extensively sampled for macro-diamonds by drilling and trenching. A total of over 25,000 tonnes of sample have been collected, although only a small proportion of the trench sample was processed, and sample from one LDD hole was not processed in the interest of rapid results turnaround (due to very high DMS yields from 'Unit 13' portions of the South Lobe). Core from the pilot holes was sampled for microdiamonds, to provide a comparison with LDD results, and to provide more robust grade and revenue estimation. The sampling method and approach is described in detail in the AK6 Kimberlite Technical Report.
Samples for macrodiamonds (+1.0 mm diamonds) were taken by means of:
All sample preparation and analysis was done by De Beers within ISO certified facilities The sampling methodology and diamond recovery process is detailed in the AK6 Kimberlite Technical Report.
The information in this section which is of a scientific or technical nature has been derived from the following technical report:
AK6 Kimberlite Project, NI 43-101 Technical Report revision and update on the AK6 Kimberlite Mine, Botswana", dated December 31, 2010 prepared by MSA Geoservices (Pty) Ltd. and authored by Messrs. Ian McGeorge, Consulting Geologist (BSc (Hons), Geol. MSc, CGeol, FGS), Mike Lynn, Senior Project Manager (BSc (Hons), Geol, MSc), Johannes Ferreira, Consulting Geostatistician (MSc, DEA Geostatistics, PrSciNat) and Rob Croll, Consulting Engineer (BSc (Min Eng)), Dave Blair, Consulting Environmental Scientist (BSc (Hons) Zool., Pri.Sci.Nat) and Dr. Kym Morton, Consulting Hydrogeologist (PhD FGS FSAIMM, Pri.Sci.Nat), each of whom is a "qualified person" within the meaning of this term in National Instrument 43-101 (the "AK6 Kimberlite Technical Report").
Copies of the above-mentioned technical reports are available under the Company's profile on SEDAR at www.sedar.com.