The History of Mining. Michael Coulson

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СКАЧАТЬ It was not until the 13th century that an advance in European technology allowed diamond cutters to cut rough diamonds, with increased confidence, to a basic number of shapes. Indian aristocrats before that, therefore, wore their diamonds largely in their natural state as crystals in a variety of jewellery and clothing settings.

      In the 16th century the Antapar region yielded many diamonds of great value, which were claimed by the corrupt ruler of the State of Vijayanagara, Kama Rayar. However, his great wealth was unable to save him from defeat and death at the hands of the Muhammadans, who invaded from the north in 1565, at the Battle of Talikota.

      Other diamond mines were worked in the region, including the famous mines of Wajrar Karur, and mines at Nandial and Kumal to the north, and also the nearby Ramulkota mines which were worked for a number of centuries in the Middle Ages. Wajirar Karur produced some large stones including the Gordonorr, a 67-carat stone, named with tongue in cheek after a Madras jeweller in the 1880s.

      Historically the mines were worked as surface deposits and heavy monsoon rains helped wash the diamonds out into alluvial channels for the miners. More recently in the 19th century, miners, often returning to historic diamond-rich areas, dug pits into the diamond-bearing ground and then brought the ore to the surface to be washed and treated. This was a difficult task as the pits were often very wet at the deeper levels (50 to 80 feet) where diamonds had been laid down in extensive, if often thin, stratum. The water and the diamond-bearing earth had to be brought out by hand. Also, the earth was of a clay quality, which made the washing a more extended and expensive process. Fortunately the diamonds recovered were often of sufficient value to make the exercise worth doing.

      In the 17th century, according to Jean-Baptiste Tavernier, the French traveller who brought a number of large diamonds back to France, there were as many as 60,000 Indians working in the diamond mining industry. Tavernier also may have been the first westerner to identify what became known as the Kohinoor diamond presented to Queen Victoria in 1849. It was a 280-carat diamond believed to have been discovered in the 4th century BC and over the centuries much fought over as a consequence of the frequently changing political face of the Indian sub-continent. Its genesis was thought to be from the Golconda mines, where the 700-carat Great Mogul stone was also discovered, as was the famous Hope blue diamond. Historically the Golconda mines produced finer stones than the Panna mines but it is the latter area where, albeit in a small way, diamond mining continues today.

      Spread as it was over many centuries, at a time when the keeping of statistical records was piecemeal at best and when the mass markets of today could not have been remotely envisaged, it is impossible to say how many carats of diamonds the Indian mining industry produced over this long period when it had almost a monopoly on world output. It is said that Muhammed Ghori, whose invasion of India in 1176 brought Islam to the country for the first time, pillaged almost 100,000 carats of fine diamonds in 30 years of tyranny before his death in 1206. It is also the case that at the turn of the 20th century Indian diamond output had fallen to less than 1,000 carats a year as Africa took up the reins of this industry.

      Brazil

      The predominance of India as the main source of diamonds began to flag in the 18th century, but fortunately in the early part of that century samples of diamonds began to reach Portugal from its South American colony, Brazil. The source of the first diamonds was the state of Minas Geraes, a region that will become very familiar when we look at gold and iron ore in Latin America later. The initial discovery was made in the area known as Serro do Frio or Diamantina, where substantial quantities of diamonds were found in rivers and streams, which led the Portuguese government to claim exclusive ownership of the area’s diamond resources.

      Originally diamond traders, afraid that Brazilian diamonds might lead to a sharp fall in the price of Indian diamonds, spread the rumour that the stones had actually reached Brazil via the Portuguese colony of Goa on India’s west coast and were Indian and not indigenous Brazilian stones at all. Brazilian traders then turned the story around by taking advantage of these rumours and acquiring some Brazilian diamonds and selling them into the Indian market via Goa at premium prices, which Indian stones could command at that time.

      However, Serro do Frio was not the only source of diamonds in Minas Geraes, and indeed the state itself had no monopoly on diamonds in Brazil once the garimpeiros – peasant diggers – inevitably joined the search. The state of Bahia was also an important diamond source and in the 19th century overtook Minas Geraes as the largest producer of Brazilian diamonds. There were also diamond diggings in the states of San Paulo, Mato Grosso and Parana. Stones from Bahia were not usually as fine or as large as those from Minas Geraes, but on occasion very high quality diamonds were found. The great proportion of Brazilian diamonds were below 1 carat, a handful were of greater size up to 20 carats, but very large stones were extremely rare. The largest found – the Star of the South – in Bogagem, Minas Geraes, was 254 carats, and there were two other recorded finds of plus 100-carat stones. Altogether this was a rather poor hoard compared with the output from the new diamond fields of South Africa.

      When diamonds were first produced in Minas Geraes the cost of production was higher than in India, but despite that output rose and by the middle of the 19th century around 6 million carats of diamonds had been mined in the state, with a value of around $50 million, and around a further 4 million carats had come from other states. In Minas Geraes one of the key watercourses carrying the diamonds was the Rio Jequetinhonha; for Mato Grosso it was the Paraguay River and its tributaries. Digging took place during the dry season when the rivers could be temporarily diverted along a specially dug course and the mud beds of the river could then be dug down to around ten feet and the spoil be transported to treatment areas where, when the rainy season began, the dried mud could then be washed for diamonds. Within the mud there were occasionally large concentrations of diamonds found and sometimes even gold.

      The heavy work was done by black slave labour, Brazil being one of the largest buyers of slaves. The black workers were incentivised not to secrete diamonds by being awarded their freedom if they found larger carat stones when washing the river mud, but despite that there was a high level of diamond pilfering. Nor did everyone see the discovery of diamonds in their area as unalloyed good fortune, indeed the social disruption was considerable as swathes of houses and huts with riverside locations were cleared away with the coming of the diamonds. Neither did the authorities always welcome diamond workings as these could lead to a dangerous fall-off in agricultural production.

      In addition to gem diamonds, carbonado or black diamonds were also found in Brazil in the early 19th century. As described, these diamonds were black or grey in colour and internally flawed and therefore not desirable as jewellery. However, they were usually harder than diamond and as the Industrial Revolution gained traction the need for hard drill bits in industry as well as mining, and for effective abrasives, opened up a market for carbonado that Brazil was able to supply.

      Brazil continues to mine and sell carbonado today. It also remains a diamond producer, but for a country that has produced in excess of 60 million carats of diamonds since mining started in the early 18th century, annual output of around 80,000 carats in 2008 constitutes a substantial fall from grace, although this figure may well understate real output levels due to the common incidence of diamond smuggling today. Having said that, Brazil does still remain a target for junior diamond exploration companies.

      13. Conclusion

      After an unpromising start in terms of human progress in the arts, science and economic activity – war and conflict was almost permanent and events such as the Black Death and the Great Plague provided major setbacks – the Middle Ages slowly began to witness a more promising environment. The Renaissance saw a flowering in education with exciting developments in art and the first signs of a broad revival in scientific activity for many centuries.

      As the Industrial Revolution loomed СКАЧАТЬ