Three years of exploration and underground development at the Leopard fissure are beginning to bear fruit for owner
Leopard is one of three large fissures situated on wholly owned portions of the company’s Klipspringer diamond property in the Northern Province of South Africa. Earlier this year, a small pipe immediately adjacent to the larger, parallel Sugarbird fissure to the north was mined out, yielding roughly 80,000 carats and making SouthernEra the country’s newest diamond producer.
After discovering Leopard in early 1995, following the investigation of a small pit dug several years earlier by
Miners are initially focusing on the upper 100 metres of the eastern section, dubbed “Ingwe,” employing underhand shrinkage stoping methods to mine its estimated resource of 450,000 tonnes. Ore will be stockpiled until next March, when a $2.3-million, 50-tonne-per-hour, dense-media separation plant is expected to become operational. The plant will be erected along side an existing 100-tonne-per-hour plant, which is processing ore from the adjacent Marsfontein farm — a 60-40 joint venture between De Beers and SouthernEra.
By the end of 1999, mining will commence on the top 100 metres of the western section of the fissure, christened “Ndau,” using methods similar to those employed in the eastern section. The section hosts an estimated resource of 750,000 tonnes.
Production rates are targeted at 12,000 tonnes per month, which, at the projected recovery grade of 70 carats per tonne, translates into 8,400 carats per month. The diamonds are expected to fetch an average of US$100 per carat — $26 lower than the price realized from the sale of a 4,832-carat parcel of diamonds collected from bulk samples.
Cash costs are anticipated at US$25 per tonne. The low cost is a reflection of competent host rocks and the fact that ore is accessible by adits rather than large vertical shafts.
Pursuant to the Marsfontein agreement, all diamonds produced at Klipspringer will be sold to De Beers’ Central Selling Organization.
As mining of both sections continues, the company will begin studying the feasibility of mining the deeper portions of the fissure. Drilling has intersected the dyke to 250 metres below surface, and the grade is expected to remain consistent at these depths, as fissures, unlike pipes, are generally predictable.
In all, the Leopard fissure has been outlined over a strike length of 2.1 km, along which it averages 1 metre in width while remaining open at both ends. At last report, total resources were pegged at 3.8 million tonnes grading 0.753 carat per tonne.
Meanwhile, De Beers and SouthernEra have agreed to spend $763,000 on an initial exploration program at Marsfontein. Previous exploration by SouthernEra outlined several geophysical and soil anomalies, along with a number of kimberlite targets that have yet to be fully explored.
The M1 kimberlite pipe yielded 144,882 carats of diamonds in October, during which time 26,531 tonnes of mixed overburden, weathered kimberlite, diabase and kimberlite stringers were treated.
Since August, when commercial production began, operators have pulled more than 359,000 carats from the 57,873 tonnes mined at M1, for a recovered grade of 6.2 carats per tonne. This grade, however, is skewed by the unexpectedly rich overburden and is expected to drop to the projected recoverable grade of 2.25 carats per tonne as primary kimberlite is reached.
Delineation drilling is expected to test diamondiferous gravel horizons extending to the south and southeast of the pipe. These gravels make up a portion of the stockpiled overburden.
Be the first to comment on "EXPLORATION — SouthernEra continues Klipspringer celebrations"