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Koffiefontein |
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Free State, South Africa |
| Main commodities:
Diamonds
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Koffiefontein diamond mine is located some 75 km southeast of Kimberley in the Southern Free State of South Africa.
The Koffiefontein kimberlite pipe was found in 1870 shortly after the Jagersfontein pipe, and at the same time as the first discoveries at Kimberley.
However, as a result of its low grade, the Koffiefontein pipe was only exploited on a small scale. The mine, which commenced operation in 1870, was closed on several occasions as a result of economic factors, but reopened most recently in 1987. It is expected to operate until 2013.
To date, 7.3 million carats have been produced, with the largest single gem produced weighing 139 carats.
The pipe forms part of a cluster of Group I kimberlite pipes and dykes that intrude the Mesozoic Dwyka shales and Karoo dolerites overlying Archaean basement of the Kaapvaal Craton. It originally had a surface area of 10.3 ha. It has been estimated that 1260 metres of the pipe have been eroded since emplacement at 90 Ma. The only other economically important kimberlite in this cluster is the Ebenhaezer pipe, which is adjacent to Koffiefontein, and was mined intermittently, but at an even lower grade.
In 2002, 2.155 Mt of ore were treated from the underground mine at a recovered grade of 5.2 carats per hundred tonnes to yield 0.112 million carats. In 2000, the average value of stones was of USD 228 per carat
The total reserves + resources (including Jagersfontein dumps) in 2000 were 161 Mt @ 6.3 cpht for 5 million carats of diamonds.
The most recent source geological information used to prepare this decription was dated: 2004.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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