Etruscan Resources Inc. - Ventersdorp Alluvial Diamond District

South Africa

Ventersdorp Alluvial
Diamond District Blue Gum Diamond Deposit Maps & Photos

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The Ventersdorp Alluvial Diamond District is located approximately 150 kilometers west of Johannesburg and covers over 5,000 km². The area has not been commercially exploited on a large scale. From 1926 to 1984 over 667,000 carats were produced from the District. Over the past six years, Etruscan Diamonds has been acquiring strategic properties throughout the Ventersdorp district and presently holds two mining permits and seven prospecting permits covering approximately 1,700 km² with one additional prospecting permit under application.

Etruscan Diamonds' efforts to prioritize its land holdings in the Ventersdorp District have been assisted by the results of an airborne gravity survey conducted over an area of approximately 4,000 square kilometers. The survey was conducted by Bell Geospace Ltd. of Aberdeen, Scotland for Etruscan Diamonds using its proprietary Air-FTG™ system. The survey identified a number of prospective sinkhole features and Etruscan Diamonds has initiated follow up ground surveys and drilling on several of these targets. This work has confirmed the presence of large sinkhole features as identified by the airborne survey, and the next step will be to determine the gravel volumes and undertake bulk samples to determine the grade.

Geology

Alluvial diamonds in the Ventersdorp District are found in gravel "runs" that are hosted by predominantly dolomitic bedrock of the Transvaal Supergroup. Gravel deposition has occurred in a karst environment where the dolomite walls of the host-rock are vertical; the mode of gravel deposition is not typical fluvial alluvial; periodic subsidence has taken place during deposition; and deposition has taken place over a long time (since, at least, the Mesozoic) resulting in a build-up of a very thick gravel sequence. The deepest drilling indicates that the lower gravels extend down at least to 117 meters (without intersecting bedrock). Geophysical interpretation, however, indicates that final depths of the sinkholes may be in excess of 120 meters and, potentially, up to 200 meters in places.

Mineralisation is confined to the gravel packages in-filling karst caverns etched out of the chert-rich dolomites of the Malmani Group. A general stratigraphy has been recognized in the gravel packages characterized by a clay-poor Lower Gravel Package, a Pebbly Clay Package, an Upper Gravel Package and a Clay Package. The Lower Gravel Package and the Upper Gravel Package are the principal units of economic significance as the diamond grades encountered in these units have, historically, supported commercial mining ventures.

Alluvial diamond deposits in the Ventersdorp district all share similar characteristics. The diamonds occur in a series of alluvial gravel deposits that extend for distances in excess of 12 kilometers with widths of up to 1,000 meters. The diamonds from the Ventersdorp district typically average one carat in size using a conventional two millimeter screen.