Tres-Or pegs two Guigues microdiamonds as Type II
2020-12-08 08:58 ET - News Release
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Ms. Laura Lee Duffett reports
TRES-OR ANNOUNCES TYPE II MICRODIAMONDS FROM THE GUIGUES KIMBERLITE PIPE IN QUEBEC
Two largest of Tres-Or Resources Ltd.'s recently reported microdiamonds recovered from the Guigues kimberlite in southwestern Quebec are very low nitrogen (Type II) diamonds, as revealed by microfourier transform infrared (MFTIR) spectroscopy analysis at the Saskatchewan Research Council's (SRC) diamond laboratory.
Type II diamonds lack nitrogen and famously include some of the largest, highest quality diamonds recovered at mines around the world (e.g. including the historic 1,758 Sewelo, the 1,109 carat Lesedi La Rona and the 813 carat Constellation diamonds from the Karowe Mine in Botwsana, as well as the famous +3,000 carat Cullinan diamond from the Premier Mine in South Africa), although they are rare and only make up an estimated 1 to 2% of diamond production world-wide (Table 1).
Table 1: Famous Type II diamonds from mines around the world (see references at end). Diamond Mine Locations Carats Famous for: (All US$) Notes Cullinan diamond Premier Mine South Africa 3107 Largest gem diamond in history British Crown Jewels Sewelo Karowe Mine Botswana 1758 2nd Largest gem diamond in history Discovered 2019 3rd largest gem diamond in history Lesedi La Rona Karowe Mine Botswana 1109 Discovered 2015 (sold for $53 million) Constellation Karowe Mine Botswana 813 Sold for $63.1 million Discovered 2016 Sethunya Karowe Mine Botswana 549 "exceptionally pure high color" Discovered Feb 2020 Lesotho Promise Letseng Mine Lesotho 603 D flawless - rounded irregular shape Discovered 2006 D flawless - 5th largest gem in history Lesotho Legend Letseng Mine Lesotho 910 Discovered 2018 (sold for US$40 million) Flawless D color Victor Mine Ontario 271 2nd largest oval cut diamond 102 carats Discovered 2018
Note that although the recovery of Type II microdiamonds from the Guigues Kimberlite is suggestive of the occurrence of larger stones, this does not mean that the Guigues Kimberlite will necessarily host large Type II diamonds.
SRC's analysis determined the two Type II stones from Guigues carry zero (0) ppm nitrogen. The stones were the largest of the microdiamonds recovered by SRC (as reported in Tres-Or's news release dated November 9, 2020). The larger of the two Type II microdiamonds remained on the 0.300 mm square mesh screen, and the other remained on the 0.212 mm screen. Micro- FTIR spectra were recovered for the two microdiamonds that remained on the 0.150 mm screen as well. These two microdiamonds carried 660 and 595 ppm nitrogen respectively, and are interpreted to have experienced mantle temperatures and pressures consistent with the diamond stability window (see Table 2).
Table 2: MFITR data including estimated nitrogen (N) content, mantle temperatures (T), pressure (P) and depths (kms). Note: Lack of N in the Type II diamonds preclude calculations of P and T. 2 T (degreeC) 38 mW/m geotherm Depth 3 Ga Pressure (GPa) Sample IaA (%) IaB (%) N (ppm) Type (km) 530 150um 100 0 660 IaA 1004 5.0 156 530 150um 91 9 595 IaA 1072 5.5 174 532 212um 0 0 0 II - - - 532 300um 0 0 0 II - - -
The remaining 6 microdiamonds recovered by SRC from the first Guigues microdiamond tests remained on a 0.106 mm screen, and were too small to yield a reliable micro-FTIR spectra.
Additional new microdiamond samples from the Guigues Kimberlite are currently in process at SRC. Results, including counts and nitrogen contents, will be reported as soon as available.
See Tres-Or's website (www.tres-or.com) for more details on the Guigues Kimberlite Pipe including indicator mineral chemistry plots, kimberlite descriptions and reference details.
References:
Bowen, D.C., Ferraris, R.D., Palmer, C.E., and Ward, J.D. 2009. On the unusual characteristics of the diamonds from Letseng-la-Terae kimberlites, Lesotho. Lithos, v. 112s, pp. 77-4.
Karowe diamonds: www.lucaradiamond.com
McCoy, K., 2018. That 910-carat diamond sells for cool $40 million. www.usatoday.com
About Tres-Or Resources Ltd.
Tres-Or Resources Ltd. is a Canadian resource company focused on exploring for diamonds and gold resources in the Temiscamingue and Abitibi regions of Quebec and is listed on the TSX Venture Exchange under the trading symbol "TRS". Additional information related to the Company is available on SEDAR and on the Company's website (www.tres-or.com).
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