- Tsodilo Resources Limited ("Tsodilo") (TSX Venture Exchange: TSD) is pleased to announce the availability of a detailed report on the mineral chemistry of the A15/4 drill samples from kimberlite A15 located in their Newdico (Pty) Limited license block in Botswana.
Background to the discovery of A15
Kimberlite A15 is located approximately 25 kilometers east of the Namibia / Botswana border in the Company's Newdico license block. The kimberlite lies within the Nxau Nxau kimberlite field where 23 kimberlites have been identified to date. Kimberlite A15 lies approximately 1.5 kilometers from a diamondiferous kimberlite body anomaly 40/97/07 (drillhole THC 16) discovered in February of 1998. Previous geochemical loam sampling work over A15 resulted in the collection of abundant numerous picro-ilmenite and a lesser amount of kimberlitic garnet grains.
Kimberlite A15 has a coincident magnetic and gravity anomaly with a diameter of approximately 800 - 1,000 meters. The magnetic anomaly is dipolar and roughly circular, indicative of a pipe-like intrusive body (see geophysical gravity and magnetic images on the Company's website under Images - Geophysical). The target was initially sampled with a vertical reverse-circulation drill hole in October 2004. After drilling through a 34 meter thick section of loose sand and a Kalahari-Formation silcrete, abundant coarse grains of kimberlitic ilmenite, diopside and pyrope up to 5 mm in size were visually identified in altered kimberlite from 34 meters depth.
Due to technical problems of drilling with a high groundwater inflow, the drill-hole (A15/1) was stopped at a depth of 116 meters still in primary kimberlite. The primary kimberlite appears to be a tuffisitic kimberlite breccia that is altered throughout the section. The tuffisitic kimberlite breccia contains xenoliths of regional shale, quartzite, granite and basalt throughout the section. Due to the favorable mineral chemistry of the A15/1 garnet, ilmenite and chrome diopside, a decision was made to submit a sample of A15 for micro-diamond analysis. In July and August of 2005, 3 additional 200-meter holes were drilled in A15 to collect a composite sample for micro-diamond analysis. Grains of pyrope and diopside from drill-hole A15/4 were also collected for analysis.
A 500 kilogram sample was collected and sent to the Geoanalytical Laboratories of the Saskatchewan Research Council (SRC) in Saskatchewan, Canada for processing. At present, the sample is still being processed. On November 9, the Company was informed by the SRC that due to the carbonate-rich makeup of our samples, reaction with the caustic sodium hydroxide was causing boil-overs and clogging of the 75 micron bottom screen. The SRC recommended switching to a 106 micron screen to process the sample as is now being done.
A15/4 Mineral Analysis
While collecting grains of pyrope, it was noticed that the abundance of grains with the visual characteristics of megacrystic garnet differed from A15/1 to A15/4. To investigate this, probe mounts containing 307 garnet grains and 25 chrome diopside grains were dispatched to the Euclid Geometrics Laboratory in Kitchener, Ontario, for microprobe analysis. The full set of results and the report of their Consultant Mineralogist are posted on our website at /s/MineralChemistry.asp
Summary of the A15/4 Mineral Analysis
- The mineral chemistry is characteristic of diamond-rich eclogite-dominant kimberlite. In an eclogite-dominant kimberlite, pyrope is Ca-rich and diopside is Tschermak-free (Si = 1.98 ±0.02 apfu) with a high-pressure Na-rich jadeite substitution.
- The Na-rich composition of A15/4 diopside is essentially identical to that of economic kimberlite pipes in Canada (Jericho, NWT, Kopylova et al. 1999, 2000), Russia (Grib, Arkhangelsk, Malkovets et al. 2003), and eclogitic kimberlites in western Africa (e.g., Koidu, Sierra Leone, Tompkins & Haggerty 1984), southern Africa (e.g., Koffiefontein, R.S.A, Meyer & McAllister 1984), Lesotho (Letseng, Kao, Thaba Putsoa, Matsuko and Monastery, Nixon 1973) and Botswana (Orapa, Robinson et al. 1989).
- Thermometry of the A15/4 diopside using the enstatite solvus (Nimis & Taylor 2000) indicates at least 42% of grains in the diamond zone. These A15/4 grains were altered, however, and the unaltered diopside of A15/1 indicates at least 58% of grains in the diamond zone.
- Both diopside and pyrope have a distinctly reduced crystal chemistry, with low values of Fe3+ indicating a favorable environment for the preservation of diamond, an important factor for grade. The low Fe3+ was verified in an earlier study of A15/1 ilmenite that indicated a good to excellent preservation potential for diamond and low resorption.
- Relative to A15/1, the A15/4 pyrope has far fewer megacrystic grains and far more lherzolitic grains, indicating surges of magma from lower depths in a stratified magma chamber.
- The A15 mineral compositions are comparable to those of the diamond-rich Jericho kimberlite, a (Na, Ca)-rich rock in which the diopside is jadeite-rich and the G10/G9 line separating peridotitic pyrope + diamond from pyrope + graphite is shifted towards Ca-rich compositions. This modified plot places 69% of the A15/4 peridotitic garnet and a similar percentage of the eclogitic garnet in the diamond stability field.
President and CEO James Bruchs comments: "The additional mineral chemistry confirms that A15 is clearly different that any kimberlite previously discovered in the Nxau Nxau field. In addition, the mineral chemistry for A15 garnet, ilmenite and chrome diopside matches that of economic kimberlites in Canada, southern and western Africa and Russia".
Tsodilo Resources is an international diamond exploration company engaged in the search for economic kimberlites at its Newdico and Gcwihaba projects in northwest Botswana. The Republic of Botswana is the largest producer of diamonds, by value, in the world. Tsodilo has an 81% stake in Newdico (16,800 sq. km under license) while Trans Hex Group, a South African diamond mining and marketing company, holds the remaining 19%. The southern Gcwihaba project area (6,703 sq. km under diamond license and 3,780 sq. km under base and precious metals licenses) are 100% held by Tsodilo subsidiary Gcwihaba Resources (Pty) Limited. Tsodilo manages the exploration of both license areas. The design and conduct of the Company's exploration program is the responsibility of Peter Walker, a qualified professional geologist registered with the South African Council for Natural Scientific Professions. Please visit the website, www.TsodiloResources.com, for additional information and background on our projects.
The TSX Venture Exchange has not reviewed and does not accept responsibility for the adequacy or accuracy of this news release. This news release may contain assumptions, estimates, and other forward-looking statements regarding future events. Such forward-looking statements involve inherent risks and uncertainties and are subject to factors, many of which are beyond the Company's control, which may cause actual results or performance to differ materially from those currently anticipated in such statements.
FOR FURTHER INFORMATION PLEASE CONTACT:
James M. Bruchs - President and Chief Executive Officer
E-Mail - JBruchs@TsodiloResources.com
Telephone +1 416 572 2033
Facsimile + 1 416 572 4164