DIAMOND SPECIAL — U.S. exploration targets include Crater of

It is not often that tourists will visit a park, pick up a shovel and pay a small fee for the privilege of digging all day. But that is exactly what happens at the Crater of Diamonds State Park in Arkansas.

One or two diamonds, usually industrials, turn up most days and the tourists keep what they find. But larger stones have been found, the most impressive being an unfaceted 4.25-carat yellow diamond displayed by U.S. First Lady Hillary Clinton at the 1993 Inaugural Ball.

After potentially economic diamond discoveries were made in Canada’s North, it was only a matter of time before interest in diamond exploration was rekindled in Arkansas and other American states where previous finds have been recorded.

Indeed, the history of diamond exploration in Arkansas goes back to 1906, when the first discoveries were made in what is now the state park. The deposit was mined commercially until 1929 and has since been operated mainly as a tourist attraction.

Several other occurrences of diamond-bearing lamproitic rock were identified nearby and numerous exploration programs were carried out, particularly in the 1980s. This work involved evaluation of the known intrusive province, along with regional exploration. The list of interested companies included Anaconda Minerals, Superior Minerals and Sunshine Diamond Mining. The testing during this period was not particularly encouraging. Some of the larger dia-tremes yielded macrodia-

monds, yet grades were below 0.001 carats per tonne. Some smaller satellite pipes were found to contain diamonds, but their size and quantity proved disappointing in terms of economic potential.

At least three kimberlite-lamproite intrusives were bulk-tested, with the material hauled to Colorado for processing. Again, results were not particularly encouraging, although only small quantities were tested. In response to more recent interest in the economic potential of the Crater of Diamonds, the state of Arkansas requested interested mining companies to tender proposals for work programs to evaluate the body. Four main companies are involved: Kennecott, CRA, a joint venture involving Diamond Fields Resources (TSE) and a venture involving Texas Star Resources (VSE). A first-phase program was carried out, aimed primarily at defining the size of the kimberlite-lamproite deposit. The state has given its approval for a second-phase, bulk-sampling program, but the project cannot move forward without approval from the federal Ministry of the Interior. Discussions have taken place, but there is no assurance that federal permits will be granted. Arkansas is not the only state to receive attention from mining companies. Colorado was back in the spotlight with a recent bulk-sampling program carried out by Royalstar Resources (VSE) on the Sloan pipe.

Previously, this target had been tested by several other groups, who were encouraged by the abundance of microdiamonds encountered during exploration drilling. Less encouraging, however, were the grades and sizes of the macro population during bulk sampling.

Royalstar has extracted a 3,000-tonne sample, which is being processed at Dia Met Minerals’ processing plant in Colorado. The company focused its efforts on a higher-grade facies of the diatreme, which it believes may have potential to be selectively mined. Results from the sample are expected shortly.

Meanwhile, Wisconsin and southwestern Michigan have attracted the interest of Ashton Mining of Canada (TSE) which, earlier this year, discovered a small kimberlite body in the Crystal Falls area of the latter state. No economic significance has yet been attached to this discovery. Ashton has a 51% interest in the Great Lakes project.