TSEBEBEX DIAMOND MINING PROJECT
JOINT VENTURE TRANSACTION: US$10 million
Tsebebex (Pty) Ltd
Tsebebex (Pty) Ltd, is a privately owned diamond exploration company based in Johannesburg, South Africa, which has prospecting rights on five (5) farms situated in the locality of the town of Jacobsdal in the Free State province of South Africa on the Kimberly-Jagersfontein diamond system. Jacobsdal is a small farming town in the Free State province. The town was founded in 1859 by Christoffel Jacobs on his farm Kalkfontein, and today houses 6,500 inhabitants. The tenements are Mayville, Botterhoek, Gannahoek, Wildehondeplaat, and The Park (see Fig.1).
Fig 1. Location of the tenements under prospecting near Jacobsdal in the Free State province, South Africa
The Free State Province still holds promising kimberlite potential
The Free State province in South Africa still holds huge potential for kimberlites and modern technologies have helped unlock this potential for new kimberlite discoveries in this province. The potential of the Free State to host further commercial kimberlites was first identified following research in various archives into the history of diamond mining in South Africa. This research found that in addition to the well documented iconic operations at Jagersfontein, Koffiefontein and Kimberley, a number of smaller diamond mines existed both to the east of Bloemfontein and extending west to Kimberley.
Tests and observations by the Council of Geosciences confirm the existence of eight kimberlites which exhibit Group 1 kimberlite geochemistry similar to the larger producing mines of Kimberley and Koffiefontein in the region. The existence of extensive historical working supports the nature of these kimberlites as being diamondiferous. Detailed ground geophysics followed which produced minimum sizes for the two clusters of eight kimberlite pipes of between 0.3 and 1.15 ha. This excludes extensive kimberlite dyke development along some of the properties. These sizes were determined using a combination of magnetic, electromagnetic and gravity geophysical techniques, which has resulted in strong images of the footprints of these kimberlites.
Mineral chemistry work was then undertaken to rank the kimberlites from the perspective of diamond bearing potential. The analyses of 3 100 garnets and spinels at the University of Johannesburg indicate high abundances of diamond inclusion type chemical compositions, thereby rating these kimberlites as being of high interest in terms of diamond bearing potential. The results also indicate a preponderance of G9 and a few G10 garnets, similar to the chemical signatures present in the neighbouring iconic mines at Jagersfontein and Koffiefontein.
The mineral chemistry result supports the conclusions from the previous whole rock geochemistry and from the geophysics in addition to field observations. These results justifies moving to a phased drilling programme to further determine the commercial viability of a production operation.
Kimberly-Jagersfontein diamond system
If you were asked what the biggest man-made hole in the world is, your first guess would be the Big Hole in Kimberly, but you would be wrong. Research by historian Steve Lunderstedt in 2005 confirmed that the Jagersfontein Diamond Mine, which is located on the Kimberly-Jagersfontein diamond system, was the biggest hand-excavated hole in the world, slightly larger than the Big Hole in Kimberley. The mine was dug by pick, shovel and dynamite and up until its eventual closure on 28 May 1971 the Workers at the Jagersfontein Diamond Mine discovered two of the ten largest natural diamonds that were ever found in the world - the 972-carat Excelsior diamond and the 637-carat Reitz diamond (later this stone was named the Jubilee). Equally impressive are the jewel diamonds found here which are famous for their exceptional quality, clarity and brilliance. The Excelsior diamond came from this mine in 1893 and, until the discovery of the Cullinan Diamond near Pretoria in 1905, was also the largest white diamond ever to be found. In present day terms the value of the Excelsior is estimated at R1,2 billion. Two years later in 1895 another white diamond was found and named the Reitz. During the 100-year life span of the mine several stoppages occurred, some of which included the two World Wars and the great depression, and during this time the mine produced 9,625 million carats of diamonds, mostly of jewel quality. It is estimated that due to inefficient mining methods of the past, a large proportion of diamonds from this pipe were never recovere
Fig 2. The Kimberly-Jagersfontein diamond system straddles N-W and S-E across the tenements and Jaggersfontein.
Location of the farms under prospecting with some containing known kimberlite pipes
The farms are situated in the Kimberley–Jagersfontein diamond field, and The Park and Mayville farms have known kimberlite pipes.
A detailed ground geophysical survey undertaken on eight (8) known Group 1 kimberlites at the Aim-listed Botswana Diamonds’ Free State exploration project, which is located between Bloemfontein and Kimberley, in South Africa, has indicated that the sizes of these kimberlites range from 0.3 ha to 1.15 ha.
The kimberlite sizes were determined using a combination of magnetic, electromagnetic and gravity geophysical techniques, which has resulted in strong images of the footprints of the kimberlites.
The kimberlites occur along a northwest to southeast trending kimberlite feeder system along which the diamond mines of Jagersfontein, Koffiefontein and Kimberley are located.
It is, therefore, inferred that the eight kimberlites were formed at the same time as these mines.
Fig 3. The location of the farms and the diamond field with The Park and Mayville tenements showing kimberlite pipes
The sizes of each kimberlite pipe is known, and it is believed that each could contain diamonds. The next step is to evaluate the diamond indicator minerals in each pipe to decide priorities for drilling. This would comprise an analysis of the indicator mineral chemistry for each of the pipes to determine an economic interest rating which will prioritise further work.
The Botterhoek 217 tenement is situated approximately 15 km south of Jacobsdal in the Free State and is approximately 225.183 ha in areal extent. The farm is underlain by colluvium of the Quaternary with outcrop of the Tierberg Formation of the Ecca Subgroup of the Karoo Sequence. Besides masking diamondiferous kimberlite pipes and dykes, the colluvium may be diamondiferous. The first step will be sampling the colluvium for laboratory analyses.
Fig 4. Botterhoek geological map
The Gannahoek 406 tenement is situated approximately 20 km south of Jacobsdal in the Free State and is approximately 1844.732 ha in extent.The farm is underlain by colluvium of the Quaternary with outcrop of the Tierberg Formation of the Ecca Subgroup of the Karoo Sequence. The formation was intruded by dolerite. The Tieberg Formation and doleritic sills present on the farm may be masking kimberlitic structures. Besides masking diamondiferous kimberlite pipes and dykes, the colluvium may be diamondiferous and will be analysed for diamonds and kimberlite indicator minerals.
Fig 5. Gannahoek geological map
The Wildehondeplaat 333 is situated approximately 25 km south of Jacobsdal in the Free State. The size of the farm is approximately 1511.682 ha.
The farm is underlain by colluvium of the Quaternary with outcrop of the Tierberg Formation of the Ecca Subgroup of the Karoo Sequence. The formation was intruded by dolerite.
The Tieberg Formation and doleritic sills present on the farm may be masking kimberlitic structures. The undifferentiated lineament is testimonial of tectonic instability of the project area. This lineament requires ascertaining for it may be a diamondiferous dyke. Besides masking diamondiferous kimberlite pipes and dykes, the colluvium may be diamondiferous and will analysed for diamonds.
Fig 6. Wildehonderplaat geological map
The Mayville 400 is situated approximately 10 km southwest of Jacobsdal in the Free State. The farm size is approximately 1513.963 ha. The farm is underlain by colluvium of the Quaternary with outcrop of the Tierberg and the Whitehill Formations of the Ecca Subgroup of the Karoo Sequence. The formation was intruded by dolerite. The Tierberg Formation consists of blue-grey to dark-grey shale with carbonate concretions; subordinate sandstone and siltstone in the upper part. The Whitehill Formation consists of dark grey to black shale with subordinate siltstone; iron-rich carbonate concretions in basal part. The host geology has no direct bearing to diamond occurrence in the farm.
A kimberlite pipe has been identified on the farm and captured on a 1:250,000 geological map of the Council for Geoscience which confirms the presence of the diamonds. The colluvium should be analyzed for alluvial diamonds.
Fig 7. Mayville geological map with a Group 1 kimberlite
The Park 257 is situated approximately 15 km south of Jacobsdal in the Free State and the farm size is approximately 686.599 ha.
The farm is underlain by colluvium of the Quaternary and the dolerite of the Karoo Sequence. There is no correlation between the host geology and diamond occurrence in the farm. Kimberlitic intrusions and later weathering gave rise to diamond occurrence on the farm.
A kimberlite pipe identified on the farm and captured on a 1:250000 geological map of the Council for Geoscience confirms the presence of the diamonds. The colluvium should be analyzed for diamonds.
Fig 8. The Park geological map with a Group 1 kimberlite
Project prospecting strategy
The Park and Mayville farms are located adjacent to each other and both have known kimberlite pipes. These pipes managed to erupt to the surface and were identified by remote sensing technologies. The geological connectivity of these pipes is unknown though. Geophysical methods will help to elucidate the complexity of these kimberlitic structures.
Botershoek, Gannahoek and Wildehondeplaat farms have no documented pipes. The kimberlite pipes and dykes may be present but masked by the host geology. Geophysical techniques are recommended for detailed geological mapping.
The diamondiferous colluvium in some farms should be exploited to fund detailed exploration and mining.
- It is proposed that the known pipes in Mayville and The Park should be fully explored and exploited to fund exploration of the remaining farms.
- To minimise cost it is recommended to appoint GREM to undertake the exploration.
- GREM has in-house geophysical equipment and drill rigs that can be used in the exploration campaign.
Experts believe that four processes are responsible for creating nearly all the natural diamonds that have been found at or near the surface of the Earth. The gems can be formed in the Earth’s mantle, in subduction zones, at impact sites and even in space. However, the first process is by far the most common, and it is the only one that can lead to the creation of gem-quality diamonds. The other three are responsible only for the formation of small quantities of commercial diamonds.
Diamonds that originate in the mantle are created when heat and pressure transform carbon. The mantle is nearly 161 km below the Earth’s surface, and gems that come from there are brought to the surface by kimberlite pipes, which are formed by deep-source volcanic eruptions.
Fig 9. Typical kimberlite pipe structure in the Kimberly-Jagersfontein system
Experts are also not sure where the carbon that diamonds form from originates. However, it is believed that most likely it was “trapped in the Earth’s interior at the time of the planet’s formation.”
It is believed that in some cases it seems like the carbon originated in the mantle, while in others it appears to have come from near the Earth’s surface. In the latter case, the carbon could have literally been carbon that was part of carbonate sediments or animals, plants, shells, or whatever that was carried down into the upper mantle of the Earth by the plate tectonics mechanism called subduction.
As is mentioned above, the intense heat and pressure of the mantle combine to transform this carbon into diamonds. Put very simply, each carbon atom bonds to four other carbon atoms, creating a very strong connection and it’s because of this strength that diamonds are so hard. As more carbon atoms come into the vicinity of the bonded carbon atoms, they too attach. Eventually, once enough carbon atoms have attached to one another, diamonds are formed.
Coloured diamonds are created when foreign particulates are trapped during the diamond crystallization process. Traces of different material result in different hues, as well as different hue intensities. For example, blue diamonds, which are incredibly valuable, are created when boron is introduced in the diamond formation process — it bonds to the carbon atoms, absorbing the red, yellow and green areas of the colour spectrum.
Location of kimberlite-hosted mines in Southern Africa
These volcanic rocks, that were named “kimberlite”, were to become the corner stone of the economic and industrial development of southern Africa. Following the discoveries at Kimberley, even more valuable deposits were discovered in South Africa and Botswana in particular, but also in Lesotho, Swaziland and Zimbabwe.
A century of study of kimberlites, and the diamonds and other mantle-derived rocks they contain, has furthered the understanding of the processes that occurred within the sub-continental lithosphere and in particular the formation of diamonds. The formation of kimberlite-hosted diamond deposits is a long-lived and complex series of processes that ﬁrst involved the growth of diamonds in the mantle, and later their removal and transport to the earth's surface by kimberlite magmas. Dating of inclusions in diamonds showed that diamond growth occurred several times over geological time. Many diamonds are of Archaean age and many of these are peridotitic in character, but suites of younger Proterozoic diamonds have also been recognized in various southern African mines.
Fig 10. Map showing the location of kimberlite-hosted diamond mines in southern Africa
Fig 11. Leading diamond producers: This chart shows the estimated annual production of gem-quality diamonds, in millions of carats, for the world's leading diamond-producing nations. Graph by Geology.com. Data from USGS Mineral Commodity Summaries, Natural Resources Canada, and Kimberley Process participants.