Nambia's Skeleton Coast
Nambia's Skeleton Coast is one of the most inhospitable and desolate environments on planet earth. There are hundreds of miles of dry, deserted coastline littered with shipwrecks that ran aground from treacherous crosscurrents and a pervasive nightly fog, which is the only life-giving moisture that the unique Namib desert ecosystem receives.
The Namib desert receives less than 15 mm of rain per year, and only a handful of highly specialized plant and animal species can survive in such an extreme environment. The only indigenous human inhabitants of this stark land are the Damara and Himba, who wear only simple goatskin clothing adorned with leather, metal and shell jewelry.
Richtersveld Park & Namib Coast (right) - NASA
Namibian Mining History
During the early 1900s, German prospectors were the first to attempt any diamond exploration south of the forbidden territory of 'Namib-Naukluf,' near the town of Lüderitz on Elizabeth Bay (Elisabethbucht). After a Luderitz-Aus railway supervisor named August Stauch made the first diamond discovery in 1908, and before a diamond rush could overtake the area, Stauch laid down several mining claims. One such claim, 100 miles south of Lüderitz in Ida's Valley (near Bogenfels and Pomona) proved to be a major find. The German Government branded the area from the Orange River north to Walvis Bay as 'forbidden territory' or Sperrgebiet.
The small mining town of 'Kolmanskop' (now a ghost town) was established to the east of Lüderitz, and at its zenith during the mid 1910s, the Sperrgebiet coast accounted for 20% of the worldwide diamond take. In 1920, after the first world war, Germany lost control of Namibia to the government of South Africa, and the 'Consolidated Diamond Mines of SWA' Ltd. company (predecessor to Namdeb) was formed.
In 1928, the discovery of Namibia's vast marine-terrace diamond reserves, just north of the mouth to the Orange River, slowed production in the north, and by 1956 the town of Kolmanskop was deserted and replaced by Oranjemund as Namibia's diamond headquarters. With the recent discoveries of major secondary on-shore and off-shore deposits, Namibia may well have the largest diamond reserves of any country on earth, at an estimated 1.5 billion carats!
Alluvial Mining Along Namibia's Orange River
The Orange River forms a geographic dividing-line between the nations of South Africa and Namibia. For the last hundred million years, the Orange has been carrying eroded diamondiferous kimberlite material from its source on the Kaapvaal Craton, in central South Africa and Botswana.
Diamond-bearing material was deposited in river bank gravels and alluvium as it traveled westward towards the Atlantic Ocean. Other diamondiferous material was re-distributed by wind action, settling to form eluvial deposits in the desert. Material that completed the journey was deposited in beach terrace sediments, or redistributed by northerly ocean currents, to off-shore marine deposits on the sea floor.
Orange River & Alexander Bay (right) - NASA
These secondary alluvial land and marine deposits are Namibia's only source for diamonds, but the Orange River has left an enormous amount of diamondiferous material in the vast drainage basin stretching 150 miles from Oranjemund to Elizabeth Bay. As the sea-level receded, diamond-bearing sediments were exposed, and eventually covered by blowing sand. Land-based secondary deposits must be excavated from this sedimentary layer that lies beneath a deep layer of surface sand.
Marine Mining on the Namibian Coast
As the diamond-bearing material exits the Orange River and is dumped into Alexander Bay, it is relocated by the churning effects of the prevailing ocean currents. The heavier diamonds tend to accumulate in low lying depressions, while lighter material is washed further to the north by the Benguela Current. This leads to concentrations of diamonds in specific topographical regions.
Due to the amount of stress and weathering that the stones are subjected to during their long voyage westward, imperfect stones tent to fracture and disintegrate while stones that have less imperfections are able to complete the journey intact. For this reason, marine diamond deposits tend to have a higher concentration of gem-grade stones.
Although 'marine diamond mining' using divers has been around since the 1950s, modern 'vertical' and 'horizontal' marine mining techniques were developed by DeBeers Marine Ltd. in the 1980s to mine the Namibian concessions.
Mairine Mining operations are conducted by off-shore mining vessels that vacuum material from the sea bed, scrape the sea floor with dredge pumps attached to 'horizontal crawlers,' or with 'vertical recovery' using boring drills to penetrate the sedimentary layer. Onboard separators automatically sift and sort the diamonds from the slurry, which is dumped back into the ocean.
Companies involved in marine-mining operations in Namibia are SAKAWE Mining Corporation (aka Samicor), LL Mining Corporation (Lev Leviev Group), Trans Hex, De Beers Marine Namibia Ltd. in Windhoek, Namco (now part of Samicor), and Namdeb which is a 50/50 partnership between the Namibian Government and De Beers Centenary AG. Marine vessels include the MV Kovambo, Sakawe Surveyor, and Sucrose.
