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Stellar Diamonds plc, the London listed (AIM:STEL) diamond development company focused on West Africa, announces that processing of bulk sample material at its Tongo kimberlite dyke project in Sierra Leone is yielding higher diamond grades than previously reported.
Highlights:
· Processing to date has yielded 730 carats for an increased undiluted grade of 134cpht
· High proportion of diamonds classified as gem quality, with stones of up to 6.7 carats
· Grades anticipated to further increase after re-processing of sample material
· 1,000 carat parcel being collected to confirm diamond grade and values
Stellar Diamonds Chief Executive Karl Smithson commented, “The on-going bulk sampling continues to yield high grades from the Dyke-1 kimberlite at Tongo. The new average grade of 134cpht is already 12% higher than the previously calculated resource grade of 120cpht, before any reprocessing of the sample material, which we expect will further increase the grade. We anticipate that these increased grades will enhance the project’s global resource and economics, where the independent JORC resource currently stands at 1.1milllion carats at a grade of 120 cpht for just one of four kimberlite dykes within the licence area.
“The diamond quality at Tongo continues to impress with a high percentage of gem quality stones of up to 6.7 carats in size. We expect to conclude our bulk sampling in June 2014 when a 1,000 carat parcel will be available for diamond value modelling as part of a definitive feasibility study, due for 2015. In the meantime, following our recent fundraise of £1.85 million, we look forward to advancing our Baoulé kimberlite pipe project, located in the prolific diamond region of Aredor in southeast Guinea, to trial mining in 2014.”
Dyke-1 Bulk Sampling Progress:
The bulk sample can be broadly divided into sub-samples based on their location on the kimberlite. Samples 7, 8 and 9 were comprised of predominately fresh kimberlite with granite that required drilling and blasting for extraction. However, Sample-10 was collected from an area of the kimberlite that was highly decomposed and was extracted by means of an excavator. Previous results reported during 2014 by the Company have related only to Samples 9 and 10.
All sub-samples have been measured in detail in order to calculate the dilution and exact volume of kimberlite extracted. In addition, each sub-sample was independently measured for specific gravity and moisture content in order for the dry tonnage of kimberlite to be calculated. A consequence has been to decrease the previously reported grade for Sample 9 but increase it significantly for Sample 10. The full cumulative results for all the samples processed to date are shown in the table below.
Dyke-1 Bulk Sampling Results:
To date a total of 1,271t of kimberlite and country rock have been processed via the DMS plant. This has yielded 730.14 carats of +1mm stones at a diluted grade of 57.44cpht. Taking into account the dilution the actual in-situ kimberlite grade is calculated at 133.85cpht.
As can be seen in the table below, results for Sample-10 at 201cpht are higher than other samples and this is attributed to the fact that Sample-10 is heavily decomposed and therefore needs less crushing leading to a higher liberation of diamonds during the processing when compared to the other, harder samples. Re-processing and re-crushing of the harder samples is therefore expected to liberate further diamonds, increasing the average overall grade from 134cpht. Considering that the resource grade was previously calculated at 120cpht the higher grades will have a positive impact on the project resource and economics.
