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Davenport is a freelance journalist and mining historian - jade@engineeringnews.co.za

 

 
 
The discovery of South Africa’s first four kimberlite pipes
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11th June 2010
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The initial phase of South Africa’s diamond rush, which saw 10 000 prospectors converge on the Vaal river between 1869 and 1870, proved a failure barely one year into operation.

The failure of the river diggings can be primarily attributed to the fact that there were too many hopeful diggers competing for too few alluvial diamonds.

By late 1870, all the easy pickings from the river gravel had long gone, and all the diamonds of 1 ct or greater – the only stones for which there was a market – had been won.

Before 1870 drew to a close, some £300 000 worth of rough jewels had been taken from the river gravel. Given the number of diggers working on the Vaal river, the gross profits worked out to about £60 each.

With the significant depletion of alluvial diamonds towards the end of that year, many prospectors packed up their limited possessions and returned home.

With hindsight, it is easy to question the rationale of the earliest prospectors and their frantic rush to the Vaal river in search of diamonds, given that the actual source of diamonds is kimberlite or blue ground. (Essentially, diamond deposits occur in unique geological formations where the precious gems are contained in kimberlite pipes, or diamond-bearing rock, that are the remnants of extinct volcanoes.)

However, it should be highlighted that the earliest South African diamond prospectors and even respected geologists of the day had limited knowledge of the true matrix of diamonds, despite the fact that diamonds had been mined for many centuries in India and, later, in Brazil.

In fact, at the time of South Africa’s diamond rush, it was believed that diamonds had an alluvial source, although the exact origin of the sparkling gems remained a mystery.

This was due to the fact that the diamonds of India and Brazil, which were the two main sources of the precious stones until the South African discoveries, had been found in alluvial deposits, having been washed out of their original matrix and mined in shallow deposits close to rivers.

A similar phenomenon had occurred in South Africa whereby the tops of the kimberlite pipes had been weathered down and the diamonds had been washed into the Vaal and Orange rivers, reinforcing the belief that diamonds were derived from alluvial sources.

It is ironic that South Africa’s great diamond pipes were, in fact, discovered at the time when diamond prospectors began to rush the Vaal river.

In 1869, Boer prospectors discovered diamonds at the head of two of South Africa’s greatest kimberlite pipes on the adjacent farms of Du Toit’s Pan and Bultfontein, some miles south of the Vaal river diggings.

As the true geology of diamonds was yet unknown to diamond prospectors, these ‘dry diggings’, as they came to be known, were thought likely to offer only modest rewards and, thus, received little attention during the zenith of the river diggings.

However, with the demise of the river diggings, prospectors turned their attention to these dry diggings and initiated a more systematic and intensive search for diamonds in this area.

As the finds of diamonds on these dry diggings increased, prospectors began to realise that the belief that diamonds had an alluvial origin was, in fact, false, although their exact origin still remained a mystery.

The few men who had systematically worked the dry diggings tried to keep the finds to themselves but no secrets could be contained in that rumour- hungry region.

A contemporary anecdote illustrates the impossibility of keeping the new diamond discoveries a secret for long. A small group of prospectors, curious to investigate the claims of diamond discoveries on Du Toit’s Pan, ventured south of the Vaal river towards the end of 1870, and ascertained that diamonds were in abundance on the so-called dry diggings. (In just one week, 100 diamonds were discovered.)

The prospectors quickly returned to their river camp, rounded up their belongings and friends, and hastened to the dry diggings.

As their wagons pulled out, hundreds of people curiously looked up and watched the departure.

“Before we were out of sight”, one of the drivers noted,” the majority of tents were down and oxen were being spanned to chase after us. “They forced the pace and we only managed to keep the lead, I being in the first wagon and the mob pretty close behind.”

The news of diamond discoveries at Du Toit’s Pan and Bultfontein renewed the diggers’ prospecting fever and thousands of hopeful prospectors left the river to scramble the score or so miles up country.

They pitched a new camp – the beginnings of the mining town of Kimberley – and started digging at the head of the Du Toit’s Pan and Bultfontein kimberlite pipes.

South Africa’s two other great kimberlite pipes were discovered some months later. The two pipes, which would become known as the De Beers and Kimberly mines, were discovered on an adjacent farm, Vooruitzicht, in May and July 1871 respectively.

Whereas there had been at most 10 000 prospectors at the river diggings, by the end of 1871, there were nearly 50 000 people encamped at the new dry diggings, actively exploiting the country’s richest diamond treasure trove.

South Africa’s great diamond rush, having experienced a blip in late 1870 with the demise of the river diggings, was back on course.

Edited by: Martin Zhuwakinyu

 

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