Tsodilo Resources said an independent study of its BK16 kimberlite pipe in Orapa, Botswana shows a modelled value of $710 to $386 per carat and a grade of 8 to 11 cpht.
Company president Michiel de Wit said the promising modelled size frequency distribution (SFD) grade and value at BK16 indicated that further work was needed as it could also be a high value diamond producer like the Karowe mine.
Paddy Lawless, who performed the grade and price modelling, said both were higher than the sample grade and value of the 2,076.76-dry metric tonne large diameter drilling (LDD) sample which represented 0.01 percent of the kimberlite body tonnage.
“The sample grade and value are limited due to the relatively small sample size and hence are not representative of the entire SFD of the deposit,” he said.
“The lack of large stones in the sample is due to their relatively low probability of occurrence. By using the actual size distribution of the sample (number of stones in each size class) and aligning it with a more complete 'reference SFD', grades and values were adjusted to remove the effects of the small sample size.”
He said based on the modelled diamond value and kimberlite grade additional sampling of the kimberlite was required to confirm the positive results and to improve on the diamond value.
Tsodilo had recovered 502 diamonds to date weighing 77.94 carats from three parcels of commercial size diamonds.
The parcel was dominated by white, gem-quality diamonds, many of which were G-color or higher.
“The proportion of low-quality diamonds is very low compared to other Botswana kimberlites,” said Ray Ferraris of QTS who evaluated the parcel.
”There is a general prevalence towards resorbed dodecahedron shaped diamonds, no boart quality diamonds were seen, and the presence of the high-quality Type IIa diamonds was confirmed.”
Image credit: Tsodilo Resources