Figure 1. You would also be smiling, as the author is, if you were holding a 507.5-carat diamond. This is the Cullinan Heritage Diamond, mined in 2009 at Petra Diamonds, Ltd., Cullinan diamond mine, located east of Pretoria, and photographed in June 2010 prior to cutting. The rough diamond was purchased by Hong Kong–based private jewelry retailer Chow Tai Food Jewelry Co., Ltd., for $35 million, which remains a world-record price for an uncut diamond. Howard Bell photo, 2010.
BRUCE CAIRNCROSS
South African
Diamonds
Department of Geology University of Johannesburg PO Box 524 Auckland Park 2006 Gauteng, South Africa
[email protected]
A Photographic Personal Perspective
D
iamonds, together with gold, are inextricably woven into the social, economic, and political fabric of South Africa. For more than 140 years, these two commodities have given rise to industries that have sustained the economic development of the region. Diamonds were originally the mainstay of the South African mining industry, and although South Africa no longer leads the world rankings, diamonds still provide employment and money for many individuals and companies. All photos by Bruce Cairncross unless otherwise noted
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Dr. Bruce Cairncross is head of the Department of Geology at the University of Johannesburg and a consulting editor of Rocks & Minerals.
Figure 3. South African diamond deposits. Map used with permission of the Council for Geoscience, Pretoria, South Africa.
Figures 4 and 5. Now and then: (Left) The mine headgear at the “Big Hole” Kimberley mine, photographed in 2001. (Right) The earlier photograph is from Gardner F. Williams’s 1906 book The Diamond Mines of South Africa.
Figure 2 (left page). The Marsfontein kimberlite mine located close to Mokopane in the Limpopo Province, South Africa. Most kimberlites are not diamondiferous. This one was thought to be uneconomical until intensive exploration revealed a diamond-rich deposit. This was an extraordinary success story, as the kimberlite was mined for only four years, from 1998 to 2002, but, to quote: “This deposit, although small, repaid all capital outlay with its first 3.4 days of production. In total, some 1.826 million carats were recovered from 970 347 tonnes of kimberlite, equating to a grade of 188 carats per hundred tons of [kimberlite]” (http://www.portergeo.com.au/database/ mineinfo.asp?mineid=mn938, para. 2; accessed June 2013). Volume 89, January/February 2014 77
Figure 6. Precarious living! It is unwise to have a house built on diamondiferous gravels. This scene was photographed along the banks of the Vaal River where all of the diamondiferous alluvial deposits have been mined out from around the building, leaving it on an “island” of gravel.
Figure 7. A general view of the type of alluvial gravel mined along the banks of the Vaal River in South Africa close to Barkly West. This is a scene from the Waldeks Plant, worked by the Cloete family during the late 1990s.
Figure 8. The ubiquitous grease table at the Cloete workings, Waldeks Plant. Diamonds are hydrophobic (i.e., repel water), and this physical property is used to separate diamonds from their host gravel. While the sieved, fine-grained gravel (called bantams by the diggers) travels across the watersoaked layer of yellow grease, diamonds remain dry and stick firmly in the grease, from which they are recovered. Operations photographed at the Cloete’s Waldeks Plant.
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Figure 9. Kimberley has some stately mansions that were built during the early diamond mining era. This is Dunluce. Originally built for the diamond buyer Gustav Bonas in 1897, the house was purchased in 1902 by John Orr who founded the luxury goods retail firm of the same name. Dunluce stayed in the Orr family until 1975 when it was purchased by Barlow Rand who restored the house and donated it to the local McGregor Museum.
Figure 10. Modernday mining operation on alluvial gravels on the Vaal River at the Waldeks Plant. Gravel is excavated from nearby and trucked to sieves where it passes through various-sized meshes. Large diamonds (if present) are handpicked off these sieves while the final fine-grained fractions are taken to the grease tables for final processing (see fig. 8).
Figure 11. The old De Beers opencast mine seen in 2001. Today, it has been completely filled in with slimes and is a haven for water birds.
Volume 89, January/February 2014 79
Diamonds were first discovered in South Africa in 1866 when fifteen-year-old Erasmus Jacobs picked up a diamond on the banks of the Orange River near Hopetown in the present Northern Cape Province. This stone, the Eureka, weighed 21.25 carats and was later faceted into a 10.73-carat gem. Three years later, an 83.5-carat diamond, the Star of South Africa, was found, prompting the first diamond rush to the region. These were alluvial diamonds found in old river gravels deposited by the Vaal and Orange rivers. Today, alluvial diamonds are still being successfully exploited along the same ancient river terraces. In 1870, a 50-carat diamond was found some distance away from the alluvial diggings on the Jagersfontein farm. Although it was not recognized at the time, this discovery was made in the weathered, igneous host rock, kimberlite, and not in the alluvial gravels. (JagersfonFigure 12 (above). A 138-carat near-flawless white diamond mined from the alluvial gravels in the Barkly West area. Diamond courtesy of Bennie Cloete, CS Diamonds, Kimberley. Figure 13 (left). Two of the specimens from the A. F. Williams collection superimposed against his two-volume The Genesis of the Diamond. De Beers specimens, formerly in the A. F. Williams collection. Figure 14 (below). Some South African diamond mining memorabilia. The ceramic bottles were dug by Chris Smit from the late nineteenth-century Kimberley rubbish dump that, to this day, still yields such artifacts. These bottles are highly collectible. Two samples of kimberlite are seen in the right of the picture.
tein was, therefore, the first kimberlite discovered in South Africa and was mined from 1870 to 1931 and from 1949 to 1971. The 997.5-carat Excelsior Diamond, the second largest diamond ever found in South Africa, came from Jagersfontein in 1893. The 657-carat Jubilee Diamond was also found here in 1895.) Shortly after 1870, diamonds were also found at Dutoitspan and the adjoining farm, Bultfontein, in 1871. These two kimberlite pipes are only a few kilometers apart, and a tent-town, called Beaconsfield, soon sprang up; today Beaconsfield is one of the suburbs of Kimberley. The Kimberley mine (the “Big Hole”) and the De Beers kimberlite, were discovered in 1871. The town center of 80 ROCKS & MINERALS
Figure 15 (left). The famous 616 Diamond, mined from the Dutoitspan mine in 1964. It weighs 616 carats and is the largest uncut yellow octahedral diamond in the world. Figure 16 (right). A high-quality, alluvial 65-carat yellow octahedral diamond mined by the Cloete family at their operation on the Vaal River at Waldeks Plant, west of Barkly West. Diamond courtesy of Bennie Cloete, CS Diamonds, Kimberley. Table 1. South African diamond production statistics.
Year Production (carats) 2000 10,780,235 2001 11,238,410 2002 10,905,889 2003 12,666,536 2004 14,294,662 2005 15,776,427 2006 15,153,542 2007 15,250,079 2008 12,901,018 2009 6,118,974 2010 8,868,390 2011 about 7,000,000
Source: Department of Mineral Resources (http://www.dmr.gov.za/publications. html; accessed Oct. 2013).
Kimberley is located between these two pipes. The Kimberley mine closed in 1914 although the dumps are still being periodically reworked for diamonds. This kimberlite is famous for being dug entirely by hand. The 153.5-carat Porter Rhodes Diamond came from this mine in 1880, and the 287.4-carat yellow Tiffany Diamond is also believed to have come from the Big Hole. The De Beers mine, which is close to the Big Hole, was the source of two famous diamonds: the 457.5-carat Victoria, found in 1884, and the 439.8-carat De Beers Diamond, discovered in 1888. Subsequent discoveries of clusters of diamond-bearing kimberlite pipes soon followed after the initial Kimberley pipes, and today the main producers are located in the Northern Province (Venetia mine), Gauteng Province (Premier mine), and Northern Cape Province (Finsch mine). Venetia mine is several hundred kilometers north of Kimberley in the Limpopo Province, approximately 50 kilometers west of Musina (Messina). Of all the kimberlites in the world, the Premier mine has produced the larg-
est gemstones. The mine has yielded more than three hundred diamonds over 100 carats. Of all the large (more than 400-carat) diamonds mined in the world, 25 percent have come from the Premier mine. At the top of the list is the Cullinan, the largest diamond ever found, weighing 3,106 carats (621.2 grams). Found on 5 January 1905, it was purchased from Thomas Cullinan in 1905 by the Transvaal government under Gen. Louis Botha and presented to the British Crown. Nine large, brilliant stones and ninty-six smaller brilliants were cut from the rough diamond. The largest of these, the 530.2-carat Great Star of Africa, is set in the imperial scepter of the British Crown Jewels. Other noteworthy Premier mine gemstones include the 599-carat De Beers Centenary, found in 1988; the 128.25-carat Ice Queen; the 353.9-carat Premier Rose, found in 1978; the 426-carat Niarchos; the 67.89-carat Victoria Transvaal; and the 240.8-carat (rough) Taylor-Burton, cut into 62.4 carats. In contrast to kimberlite-hosted diamonds, alluvial diamond deposits originate from eroded kimberlites. The Vaal and Orange rivers are the two main river systems that transport and deposit diamondiferous gravel. The Vaal River connects with the Orange that then flows westward into the Table 2. World’s diamond production (2011).
Country Percentage Botswana 27 Russia 19 Canada 18 South Africa 12 Angola 8 Namibia 6 Other 10
Source: Chamber of Mines, 2012 (http://www.bullion.org.za/content/?pid=126 &pagename=Introduction+to+the+Chamber?pid=7&pagename=Publications; accessed Oct. 2013).
Volume 89, January/February 2014 81
Figure 17. A 5-mm diamond crystal in eclogite from an unnamed South African diamond mine.
Figure 18. A fancy pink 9-carat alluvial diamond mined in 2003 from the alluvial gravels, Barkly West district, Northern Cape Province, South Africa. Diamond courtesy of Bennie Cloete, CS Diamonds, Kimberley.
Figure 19 (below left). An 8-mm diamond in kimberlite matrix from the Kimberley mine. De Beers specimen, formerly in the A. F. Williams collection. Figure 20 (below right). A 7-mm modified octahedral diamond in kimberlite matrix from the Dutoitspan mine, Kimberley. De Beers specimen, formerly in the A. F. Williams collection.
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Some African Diamond Stamps And First-Day Covers
Volume 89, January/February 2014 83
Figure 21. A parcel of 102.6 carats of alluvial diamonds mined at the Cloete’s Waldeks mining operation in 1999. Diamonds courtesy of Bennie Cloete, CS Diamonds, Kimberley.
Atlantic Ocean where a third category of diamond deposits, namely offshore or marine diamonds, are deposited. The alluvial diamonds are mined from prehistoric gravel deposits. Most of the operations are on a relatively small scale compared to the large kimberlite mines; nonetheless, they do produce significant volumes of gemstones. Large diamonds are occasionally mined; for example, the 511-carat Venter Diamond was mined from alluvial deposits. The largest alluvial diamond ever found in South Africa, the 726-carat Jonker, was found in a stream that flows close to the Premier kimberlite pipe near Pretoria. Marine or offshore diamonds account for only a small percentage of diamond production, but 95 percent of marine diamonds are high-quality gemstones. The reason for this is that most of the flawed or fractured diamonds are destroyed during transportation in the rivers, with only the most robust gemstones surviving the rigors of transport. However, the reserves of offshore diamonds are large, calculated at 1.5 billion carats. There are operational problems involved in offshore mining that require special equipment and engineering techniques, but these are being overcome and marine diamond production should show a steady increase in the future.
Figure 22. The Bellsbank mine, located in the Barkly West district, South Africa. Not all diamond-bearing kimberlites are circular volcanic pipes. Some occur as intrusive dikes, such as this example that was mined out several decades ago.
Figure 23 (above). Four colored diamonds from the Kimberley mines. The total weight of the four stones is approximately 12 carats. De Beers specimens, formerly in the A. F. Williams collection. Figure 24 (left). Five unusually shaped, gemquality diamonds. The stone on the left is 28 mm in length. De Beers specimens, formerly in the A. F. Williams collection.
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I have been fortunate during the past approximately twenty years to have seen and photographed some spectacular South African diamonds. One of the reasons is that my wife’s family has been mining diamonds in the Kimberley– Barkly West region for decades. They have the entire business of diamonds covered, from mining alluvial diamonds to selling the rough stones via tender from their Kimberley offices. From time to time they have unearthed some large gemstones that I have been asked to photograph. Another reason why I have seen some special diamonds is that in the late 1990s De Beers allowed me to photograph some of the diamonds belonging to Alpheus F. Williams (deceased), after whom the mineral afwillite was named. He was the general manager of De Beers in the early twentieth century and collected diamond crystals from the company’s mines. He, together with his father, Gardner F. Williams, wrote two benchmark books dealing with diamonds: The Diamond Mines of South Africa and The Genesis of the Diamond. This collection of diamonds is kept in Oppenheimer House in downtown Kimberley. More recently, in 2010, I was fortu-
Figure 25. Diamond mining in Kimberley in the early days was tough, as attested to by some of the old tombstones in the historic Kennilworth cemetery. Many miners traveled from around the world to make their fortunes in the diamond fields, but not all survived to enjoy their profits.
Figure 28. An unusual octahedral diamond. The corners of the octahedron are inverted, projecting inward into the crystal; this has overgrown an earlier-formed modified dodechahedral diamond. De Beers specimen, formerly in the A. F. Williams collection.
Figure 26 (above). An 8.9-carat diamond enclosing a garnet xenocryst (left side of the diamond). De Beers specimen, formerly in the A. F. Williams collection. Figure 27 (right). Two twinned diamonds. The stone on the left is 13 mm; the total weight of both diamonds is 9.04 carats. De Beers specimens, formerly in the A. F. Williams collection. Volume 89, January/February 2014 85
Figure 29 (above left). Several dozen carats of various fancy colored diamonds from alluvial diggings in and around Kimberley and Barkly West. Diamonds kindly loaned by Bennie Cloete of CS Diamonds. Figure 30 (above right). The title page of Gardener Williams’s seminal book on diamonds of South Africa. Lying on the page are approximately 40 carats of diamonds mined from alluvial gravels in the Vaal River close to Barkly West. Diamonds courtesy of Bennie Cloete, CS Diamonds, Kimberley. Figure 31 (right). The 507.5-carat Cullinan Heritage Diamond, seen to scale on the hand of the author’s wife, Theresa. (The problem with taking photographs such as this is one’s spouse expects a similar-sized diamond as a future wedding anniversary gift!)
nate to see and photograph the 507.5-carat Cullinan Heritage Diamond (valued at $35 million) prior to its being cut. Photographs of these and other diamonds as well as diamond-related images are shown here. ❑
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