The Rooiberg alluvial diamond project of Redaurum (RRK-T) is on its way to minehood.
The company has applied to the South African government for a licence to develop its 4,300-ha Rooiberg property, where large volumes of diamond-bearing alluvial gravels have been discovered.
Bulk samples taken from six sites have all yielded diamonds. More than 160 gem-quality diamonds were recovered, the largest of which weighed 1.25 carats.
Most of these are similar to diamonds mined by Redaurum at Quaggas Kop, 6 km upstream, but a second distinct population of diamonds of a generally higher quality is becoming evident among the stones recovered on Rooiberg. The Quaggas Kop alluvial mine has been producing diamonds averaging 85% gem quality, which in 1996 sold for prices averaging US$209 per carat.
Drilling at Rooiberg has delineated 7 km of the meandering course of a buried Miocene-age paleochannel of the Sout River, which runs through the property.
An estimated 10 million tonnes of potentially diamond-bearing gravel is contained in that length of the buried river valley, averaging 500 metres in width.
The gravel-filled paleochannel extends beyond the Rooiberg boundary into an adjoining property, known as Arizona. Redaurum has acquired exclusive prospecting rights to the 5,860-ha Arizona property.
Drill intersections into the limestone bedrock of the paleochannel on Rooiberg reveal evidence of sinkhole structures, or large solution cavities filled with gravel. One of the sinkholes is more than 20 metres deep.
Redaurum notes that similar gravel-filled limestone solution cavities of Miocene age elsewhere in South Africa have proved to be trap sites for substantial grades of high-value alluvial diamonds.
The bulk-testing program in progress has been confined to the most accessible near-surface gravel deposits. These represent an upper terrace of the Miocene River Valley. Evidence from other alluvial diamond mines suggests Rooiberg’s best diamond recovery grades are likely to come from deeper-lying gravel in bedrock scour channels and in the sinkholes. Bulk samples of the basal and sinkhole gravels will be excavated and tested for diamond content over the next six months.
Mining of the high terrace gravels is expected to begin during the current quarter.
Meanwhile, an agreement has been executed granting Redaurum exclusive rights to a potential diamond-bearing property in Wyoming. The exploration target is a topographic depression comprising 4.7 ha.
Heavy-mineral samples of alluvium, taken immediately down-slope from the site, returned pyropes and chrome diopsides, indicating the potential presence of kimberlite. The company’s geologists consider that the surface characteristics, geophysical signature and kimberlite indicator mineral anomaly represent a possible new field.
Redaurum officials have stated that this acquisition represents the first stage in the company’s plan to expand its operations in North America and “take advantage of its unique position” as the only commercial diamond producer in the U.S.
The company will begin drilling at the Wyoming property shortly, with results expected in the third quarter.