Minerals exploration company Impact Minerals has started a significant exploration programme for uranium 
on its areas of prospecting licences, which stretch over more than 27 000 km2 in Botswana.

Impact Minerals director Dr Mike Jones says that the company’s prospecting licences cover 350 km of the strike extensions of rocks that host many significant uranium deposits throughout Southern Africa, including the adjacent uranium deposits owned by uranium 
exploration company A-Cap Resources, at the Letlhakane project, near Serule.

A-Cap has reported an inferred resource of 98-million pounds of uranium oxide at an 
average grade of 158 parts per million (ppm) 
and a cutoff grade of 100 ppm, in deposits hosted by near-surface calcrete and by Karoo group sedimentary rocks. A bankable feasibility study on the Letlhakane project is in progress.


Uranium Deposits
Jones says that Impact’s licences are prospective for three types of uranium deposits. 
The first is for deposits hosted by Karoo sedimentary rocks, which host a number of large uranium deposits throughout Southern Africa, including at Letlhakane. The second is uranium hosted by calcrete in Cainozoic palaeochannels, a style of mineralisation well known in Australia and Namibia. Thirdly, Impact’s licences are prospective for deposits within playa or salt lakes, which, in Australia and elsewhere in Africa, are known to host significant uranium deposits.

“Impact has identified 18 such target areas with a combined strike length of more than 400 km within its licences. These generally 
comprise elongated regions within which there are variably exposed calcrete outcrops and outcrops of prospective Karoo sedimentary rocks. Many have elevated surface uranium responses in the regional airborne radiometric data and in ground spectrometer 
readings,” Jones asserts.

He adds that five of these target areas have 
been prioritised for follow-up work on the basis of the widespread surface uranium
anomalism in calcretes and sandstones, backed by regional mapping, ground reconnaissance work and sampling. The areas are called Sua, Lekolobo, Kodibeleng, Ikongwe and Shoshong.

Large soil geochemistry programmes on these targets are in progress to identify specific drill targets, with the aim of drilling at least two of these prior to year-end, subject to weather constraints and access during the wet summer season.

Priority Target Areas
The Lekolobo target area is south of, and 
adjacent to, A-Cap’s Letlhakane project. Jones explains that Impact’s licences cover the interpreted south-western extension of the uranium mineralisation at Letlhakane, including the newly discovered prospects at Serule West and Serule East. Impact’s target 
is defined at surface by a 12-km-long area of up 
to 20 ppm of the equivalent uranium (eU) con-
tent of materials calculated from both airborne radiometric data and measurements taken with an industry-standard portable 
spectrometer in the airborne radiometric data.

“At Letlhakane, the Karoo-hosted primary uranium mineralisation occurs in a fault-bounded sedimentary basin as well as in Karoo-aged palaeochannels that feed into this basin and which are recognisable in the radiometric data. The western and south-western extensions of the uranium mineralisation at Letlhakane disappear under younger cover rocks, calcrete and alluvium towards Impact’s tenements,” he says.

The geological setting at Impact’s Lekolobo target area is similar to that at Letlhakane. Outcrops of Karoo sandstone contain up to 66 ppm eU and are interpreted to be part of a west-draining Karoo palaeochannel that 
enters a sedimentary basin hidden beneath the Kalahari sand and calcrete.

The Kodibeleng, Ikongwe and Shoshong target areas are each about 20 km long and interpreted as Kalahari palaeochannels containing calcrete. They are buried by up to 
5 m of sand and soil and are prospective for calcrete-hosted uranium deposits, such as Yeelirrie, in Western Australia, and Langer Heinrich, in Namibia. The headwaters of all three channels drain from Archaean-, Proterozoic- and Karoo-aged rocks that all contain elevated uranium values of up to 
80 ppm eU. Jones asserts that such uranium-
enriched rocks comprise a fertile source for uranium that may deposit in the younger channels.

“At one locality in the Kodibeleng palaeochannel, the calcrete has been eroded to reveal 
up to 3 m of calcreted Kalahari sandstones and conglomerates which, at the base, contain up to 35 ppm eU, a ten-times-greater 
response than at surface,” he points out.

The Sua target area comprises two large anomalies, 200 km2 in extent, of elevated uranium values up to 10 ppm eU identified in the regional airborne radiometric data. The eastern anomaly is 12 km long and up to 
5 km wide, and the western anomaly is 20 km long and 15 km wide and, Jones adds, that it probably continues to the west. Soil profiles exposed in shallow trenches within the western area have uranium values up to 15 ppm eU
for up to 2 m below the surface, which 
indicates that the uranium is not a surficial feature and may represent a soil anomaly over a larger source at depth.

“The Sua target has similarities to the Manyoni project, in Tanzania, owned by uranium exploration company Uranex, where uranium mineralisation has been discovered 2 m below the surface of playa lakes. Here Uranex has reported an inferred
resource of 46-million tons at 151 ppm ura-
nium oxide for a contained 15-million pounds of uranium oxide within an area of about 
5 km2,” says Jones.

He adds that Impact’s targets in Botswana have the potential to host very large deposits of uranium mineralisation in a country ranked in first place by the Fraser Institute in its 2009 survey of mining jurisdictions in Africa.