• EXCURSION
the morphology of the pothole , but also to a great extent on where it is situated relative to the run .
The diamond gravels in the potholes and sinkholes are associated with large chert boulders , which proved to be a challenge in the recovery of the alluvial material . Some of the paleo-potholes and paleo-sinkholes were exposed on surface and targeted for mining . The remaining paleo-potholes and paleo -sinkholes were however obscured by the surface cover and dense vegetation in places . It was only with the advent of geophysical gravity surveys , that the remaining extent of the pothole and sinkhole locations were revealed .
Exploration and Mining No new prospecting was allowed in the area until 2004 . A couple of companies engaged in exploration in the area with varying degrees of success . The evidence of the hand pits for assessing gravel , trenches for taking bulk samples , large diameter Bauer boreholes ; and smaller reverse circulation ( RC ) drill holes remain visible . The average recovered grade reported in the new area for 100m ³ was 3.22ct . The drop in uncut diamond prices during this time , however resulted in operations being unable to operate viably .
The proximity of the Bakerville alluvial diamond deposits to existing infrastructure , such as the N4 and N14 , grid power and sufficient ground- and surface water for processing , makes the prospect of re-developing the area viable .
Other Minerals and Mining The main mining activity in the area is the cement plant located outside of Lichtenburg , producing product for domestic consumption . The large building visible on the horizon and the steady stream of trucks moving around the main roads of Lichtenburg are evidence of this .
The gravel runs also contain sought-after beautiful yellow , orange , red or brown semi-translucent chalcedony . These semi-precious gemstones are naturally rounded and polished and easy to identify in the old gravel heaps . Mineral collectors are able to find mostly fragments , with full carnelians with patterns inside being scarce .
The area also contains manganiferous horizons which are associated with the dolomite country rock chemical weathering . There has been a number of small-scale mining operations that were able to recover manganese through a dense medium separation process .
Slightly further towards Zeerust is the historic Witkop fluorspar mine , where the current operators are reprocessing the dump material to produce agricultural lime .
Who knows what the future may hold for this area steeped in history and possible future propects ? •
Dr Nicolaas C Steenkamp is an independent consultant , specialising in geological , geotechnical and geometallurgical projects and mining project management . He has over two decades of industry experience with global exposure . ( ncs . contract @ gmail . com )
22 • African Mining • October 2023 www . africanmining . co . za