Mine Kimberley

Lawless P. J., Gurney J. J., and Dawson J. B. (1979) Polymict peridotites from the Bultfontein and De Beers mines, Kimberley, South Africa. In The Mantle Sample Inclusions in Kimberlites and other Volcanics (eds. F. R. Boyd and H. O. A. Meyer). American Geophysical Union, Washington, DC, pp. 144—155. 

Zircon occurs in the Ural Mountains Trentino, Monte Somma, and Vesuvius. Italy Arendal, Norway Ceylon, India Thailand at the Kimberley mines, Republic of South Africa Madagascar and in Canada in Renfrew County, Ontario, and Grenville, Quebec. In the United States, zircon is found at Litchfield, Maine Chesterfield, Massachusetts in Essex, Orange, and St Lawrence Counties, New York Henderson County, North Carolina the Pikes Peak district of Colorado and Llano County, Texas. 

Without the high regard, that gem diamonds enjoy in our society, the extraction of natural diamonds would be completely uneconomic. Even in the rich Kimberley seams in South Africa, only 2.5 carats (0.5 g) of diamonds are obtained per t of processed rock, only 0.4 carats of diamond being obtained in 1985 in the Premier Mine (also in South Africa). 

The De Beers Diamond found in 1888 in the De Beers mine at Kimberley was pale yellow and weighed 88 grams or 440 metric carats. When cut it yielded a magnificent brilliant of 234 5 carats. 

There are many interesting international aspects to the history of gems. Economies of countries have been based on gem production. Though not usually as bad as precious-metal mines, the effect of gem mines on the environment can be very negative. The Kimberley mine... 

Diamond size is expressed in carats 1 carat = 0.2 g. The mines at Kimberley have produced a total of more than 200 million carats since the 1870s. Almost half of South Africa s diamonds are of gem quality. The largest producer of gemstone diamonds in southern Africa - and in the world - however is Botswana. The world production of natural diamond in the year 2001 is shown in Table 39.3 [39.6]. 

Figure 1.B Zebra mudstone from Argyle Downs Station, East Kimberley, Western Australia. See [ 21al. The dark bands are portions of the mudstone containing 5-6 chemically-precipitated hematite. The light bands ( mm thick) contain only 1% hematite. In other places in the area the rock is not banded but spotted As one moves farther south-west these spots become more mnnerous and coalesce. Most stages can be found between the spotted rock and the well known striped red and white rock." [21a, p. 5 ] Sample provided by A.F. Trendall, Department of Mines, Perth, Western Australia.

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