The Tiris project is 100% owned by Tiris Ressources SARL, which is 85% owned by Aura Energy Ltd and 15% by the Mauritanian Government’s Agence Nationale de Recherches Géologiques et du Patrimoine Minier (ANARPAM).
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Summary:
The Tiris resources lie in the north-eastern part of the Reguibat Craton, an Archaean (>2.5 Ga) and Lower Proterozoic (1.6-2.5 Ga) aged complex composed principally of granitoids, meta-sediments and meta-volcanics. The resources lie within Proterozoic portions of the craton.
In Aura’s resource zones, the underlying rocks are pre-dominantly granitic and of two main types:
• Pale grey medium-grained granite and granodiorite with coarse phenocrysts of plagioclase, generally unfoliated and forming low smooth outcrops. The uranium content is low, typically 1 to 2 ppm.
• Finer-grained red to pink porphyritic granite, less abundant than the grey granite. This granite typically has higher uranium content in the range 5 to 20 ppm and is therefore a moderately ‘hot’ granite. The red granite is typically fractured and foliated and is believed to have formed by alteration of the grey granites in zones of deformation.
All the resource zones lie beneath very flat land surfaces covered by surficial hamada and thin aeolian sand deposits. These largely cover the basement rocks, which appear only as scattered outcrops.
The Mineral Resources occur in five separate areas (Hippolyte North, Hippolyte South, Lazare North, Lazare South and Sadi) within a rectangle around 32 km north-south and 42 km east-west. All mineralisation forms flat lying tabular bodies ranging in thickness from 1 to 12 m.
Mineralisation
The uranium resources lie predominantly within either weathered, partially decomposed red granite or in colluvial gravels developed on or near to red granites. The resources are believed to have developed within shallow depressions or basins, where colluvial material has accumulated in desert sheet wash events.
Calcrete-hosted uranium mineralisation of several metres in thickness occurs in gravels and weathered granite at surface to a depth of 8 metres, or under a very thin (<30cm) veneer of windblown sand. The weathered veneer of relatively unconsolidated material that overlies fresh rock is typically less than 5 metres in thickness, although locally it can occur up to 12 m depth.
The mineralised bodies form laterally continuous, single, thin sheets overlying fresh rock, usually granite. This offers the opportunity for easy, low-cost mining and little or no crushing.
Uranium mineralisation occurs principally as carnotite K2(UO2)2(VO4)2.3H2O, occurring as fine dustings and coatings on granite or granite mineral fragments usually mixed with white powdery calcium carbonate. The carnotite grain size is mostly ultrafine micron scale. The deposits appear to have formed by near-surface leaching of uranium from the uraniferous red granites by saline groundwaters during the wet Saharan “pluvial” periods. There have been many of these periods over the past 2.5 million years, the most recent ending only 5,900 years ago. Evaporation during the subsequent arid periods caused the precipitation of the uranium vanadates, along with calcium, sodium and strontium carbonates, sulphates and chlorides.
Dimensions
The Mineral Resources at Hippolyte North at a cutoff of 100 ppm U3O8 occur in an area 6 km eastwest and 5.5 km north-south. This region is comprised of several separate areas that range in plan dimensions from 500 m to 1.1 km wide and 500 m to 2.2 km long. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 11 m below surface.
The Mineral Resources at Hippolyte South at a cutoff of 100 ppm U3O8 occur in an area 5.6 km eastwest and 5.4 km north-south. This region is comprised of three isolated areas each with a north-south length of around 1.3 km and an eastwest length that ranges 400 m to 1.1 km. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of six metres below surface.
The Mineral Resources at Lazare North at a cut-off of 100 ppm U3O8 occur in an area 4.5 km eastwest and 2.4 km north-south. This region is comprised of three isolated areas. The smallest of these areas has an east-west length of 900 m and a north-south length of 550 m. The largest area has an east-west length of 2.2 km m and a north-south length of 1.8 km. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 12 m below surface.
The Mineral Resources at Lazare South at a cut-off of 100 ppm U3O8 occur in an irregular shape with an east-west length of 5.5 km and a north-south length of 2.7 km. The largest area has an east-west length of 2.2 km m and a north-south length of 1.8 km. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 10 m below surface.
The Mineral Resources at Sadi at a cut-off of 100 ppm U3O8 occur in an irregular NNW trending area with an east-west length of 5 km and a north-south length of 9 km. The upper limit of the mineralisation occurs at surface and the reported resources reach a maximum depth of 14 m below surface.
Commodity Production
The Tiris mineralisation allows for rejection of 85-90% of ore mass as barren rejects, through a simple beneficiation process (scrubbing and screening). Beneficiation of the ore delivers an average grade of 1,743ppm U3O8 life of mine, with a feed capacity 500,000 tpa.
| Commodity | Units | Avg. Annual | LOM |
|
Uranium
|
M lbs
| 1.9 * | 30 * |
All production numbers are expressed as U3O8.
* According to 2024 study.