Marshall Fork yields 17-carat diamond

Partners Diamond Fields International (DFI-T) and South African-based Trans Hex Group have recovered a 17-carat alluvial diamond off the coast of Namibia, near the town of Luderitz.

The stone, which came from the Marshall Fork geological feature, is reportedly the largest ever picked from the seabed in that particular region. There are two other operators in the vicinity, namely Namibian Minerals (NMR-T) and Namdeb, the latter being a joint venture between the Namibian government and De Beers.

Diamond Fields notes that the discovery provides proof of an energetic transportation system. This, in turn, raises the possibility of finding other, similar-size stones.

Between May 2001, when mining began, and March 31 of this year, the pair mined 26,800 carats from the Marshall Fork structure. The stones averaged 0.33 carat in weight.

Diamond Fields’ share rang in at 16,080 carats, of which 12,815 carats were sold to generate a gross operating profit of $1.2 million. The junior is entitled to 60% of the proceeds but must cover 60% of the costs until it has recouped all expenditures prior to Trans Hex’s arrival in March 2001, up to a maximum of US$8.5 million. Thereafter, revenues and expenses are to be split evenly.

As part of the deal, Trans Hex must provide two airlift vessels and the necessary personnel to operate them. The second has to begin trial runs by Novemeber.

The joint venture area covers 0.5% of Diamond Fields’ Mining Licence 111, which covers 70 km of coastal waters between Hottentot Point to the north and Diaz Point to the south, centered at Luderitz. The area includes the Marshall Fork feature and the Diaz 12 zone of the Diaz Reef feature.

At last report, probable reserves at Marshall Fork totalled 1.4 million cubic metres averaging 0.3 carat per cubic metre. The reserve is spread over an area of 865,000 sq. metres.

Probable reserves at Diaz Reef stand at 3.6 million cubic metres averaging 0.13 carat per cubic metre, spread over an area of 2.13 million sq. metres. The Diaz 12 zone covers a portion of that structure.

Combined inferred resources in both features ring in at just under 1.1 million cubic metres averaging 0.19 carat per cubic metre. The estimate is exclusive of reserves and includes sediments spread over an area measuring 729,600 sq. metres.

The independent estimates, calculated by engineering firm MRDI, a division of AMEC E&C Services, are based on sampling programs carried out by BHP and subsequently De Beers Marine. A cutoff grade of 0.15 carat per sq. metre and a diamond price of US$175 per carat were assumed in the case of the reserve estimate.

All told, Diamond Fields and Trans Hex expect to recover between 675,000 and 1.35 million carats over the next seven years, when the agreement is up for its first annual renewal. The upper level takes sampling bias into consideration.