Uranium ore-forming systems of the - Geoscience Australia

Uranium ore-forming systems of the Lake Frome region5.1.3 In-situ reductantsThe Beverley Sands are generally poor in organic material. The dominantly quartzose sands arefine to medium grained and contain laminae and beds of sandy clay, silt and clay and only sparsefragments of organic material. The Alpha Mudstone, however, is rich in organic materialrepresented by plant fragments and large pieces of carbonised wood. In general organic carbon ingrey sands ranges from 0.05% to 0.5% increasing up to 2% in a few samples (HeathgateResources, 1998).5.1.4 Beverley mineralisationUranium mineralisation at the Beverley deposit occurs in predominantly tabular and lenticularzones, mainly at the contact with the organic rich Alpha Mudstone (Fig. 5.2, Brunt, 2005). Thecombined thickness of ore zones varies typically from 20 to 30 m. The principal uranium mineralis coffinite which fills voids and forms coatings on quartz grains (McConachy et al., 2006). Minoruraninite has been reported but requires confirmation. The uncemented grey sand in the ore zonealso contains pyrite, marcasite, feldspars, clays (kaolinite and montmorillonite), gypsum andalunite. Alunite and gypsum may be associated with later oxidation which also produced carnotite(Wülser, 2009).The ores contains traces of Th, Rb, Sr, Cu, Zn, Mo, V, Se and As, which are typical for sandstoneuranium systems (Heathgate Resources, 1998).Figure 5.2: North-south cross section showing uranium mineralisation (red) in the Beverley Sand,Namba Formation (modified after Brunt, 2005). Note that mineralisation is located generally at ornear the contact with Alpha Mudstone.Page 59 of 151