THE DIAMOND PAGE — More stones recovered from Crater of Diamonds

Almost half of a planned 10,000-tonne bulk sample from the Crater of Diamonds state park in Arkansas has been processed.

Under the operatorship of the state department of Parks and Tourism, a bulk-sampling program comprising 14 proposed trenches of 650 tons each is being carried out on a diamondiferous lamproite pipe.

The state’s objective is to evaluate the geology of the pipe and determine a grade.

Analysis of a further 2,619 tons of material, extracted from four trenches on the eastern portion of the pipe, revealed 86 macrodiamonds greater than 1 mm in size weighing 19.33 carats. Four of the stones weigh between 0.5 and 1 carat, while two weigh between 1 and 2 carats.

To date, a total of 157 macros greater than 1 mm in size and weighing 36.08 carats have been recovered from 4,592 tons of processed material taken from seven trenches. The recovered stones include 15 diamonds weighing between 0.5 and 1 carat, and three weighing between 1 and 2 carats.

The preliminary grade is estimated at 0.79 carat per 100 tons, or 0.0079 carat per ton. The pipe, which outcrops at surface, has a potential drill-indicated resource of 78 million tons to a depth of 600 ft.

Trenching is continuing on the southern and central portions of the pipe.

Diamonds were first discovered in the area in 1906 and mined commercially until 1929. The largest diamond recovered weighed in at 40.23 carats.

Should the state proceed with the awarding of mining rights, two groups will hold the exclusive rights to submit bids.

One group is a 51-49 joint venture between Ashton Mining of Canada (ACA-T) and Star Resources (SRR-T), and the other is a joint venture between a consortium of private companies led by Diamond Fields International, holding a 49.99% interest.