Iyunsky gold deposit in residual soil (East Salair)

Within Ursky ore cluster (EastSalair) a gold deposit with rich clay hypergene ores was discovered in the residual soil of the Iyunsky site. The mineralised zone, whichaccommodates the original hypogene pyrite mineralization area, is represented by hydrothermally altered (silicification, baritization andsulphidization) vulcanites of the Pecherkinskaya suite in the contact area with the Ancheshevskaya suite limestones. Primary sulphideores are presented by pyrite, sphalerite, galena and chalcopyrite (in the order of decrease in content); the presence of barite from 2.4 to42.8% is indicated. Ore minerals are unevenly distributed, often in the form of fine disseminations, vein lets and nests, often formingsulphide deposits in the form of lenses and plates with the length of 160-320 m to one km and the capacity of 1.6-23.2 m. In auriferousrocks within the site residual speckled clay and rubble-clay gold-bearing residual soil of the Late Cretaceous - the Palaeogene time ofthe fractured-linear type combined with contact-karst morphologic subtype is developed. The established deposit of the gold-bearinghypergene formations is 1 200 m long, 150-350 m wide at the surface exit (under the sediments), and 110-140 m and more deep. Theore deposit morphology is very complex and is defined as the initial morphology of the primary ore bodies as well as chemical substancesmigration processes and mechanical movements of loosened material in the supergene zone. The residual soil formations arepresented by the quartz-illite-kaolinite mineral type in various combinations with hydroxide-(goethite-hydrogoethite-polianitepsilomelan)-kaolinite regularly interlacing in the section. Almost all the loose formations in residual soil have higher gold-bearing capacities- from the traces to 0.1-0.5 g/t and more (up to 15-28 g/t, rarely 46.0 g/t); silver content in ordinary samples reaches up to58.6-75.5 g/t. According to the assay data of core samples gold ore bodies with marginal gold content of 0.5 and 0.6 g/t are allocated;they are represented by echelon fold lightly pitching deposits. The thickness of ore bodies ranges from 3 to 20.3-25.1 m with the averagegold content in the cross section from 0.60 to 3.84 g/t. Within the identified deposits the following changes in patterns of the mainparameters of mineralization occur. In the southeast there is a slight decrease in the level of gold in ore bodies, with an increase of theirtotal capacity. The existing ratio of mineralization parameters is reflected in the 2-3-times increase of mineralization ratio (linear) in thisdirection; it does not lead to the levelling of the total ore mass volume deficiency, which decreases to the south-eastern flank of the depositin general. The selected ore bodies are also accompanied by thicker areas of schlich gold. According to the mineralogical analysisof schlich samples the concentrations were found of gravity gold of fine-grain class of grains up to 1.087-7.040 g/m3, with individualsamples reaching 31.704 g/m3 (4862 grains or 158.52 mg of metal per one schlich sample). All the identified mineralogical types of oreshave high technological characteristics of enrichment using three promising technologies for this type of material - gravitation, gravitationand cyanidation, and heap leaching. The main expected technical and economic indicators of the development of the probable depositof the gold-bearing residual soil allow high evaluation of the prospects of continuing geological evaluation survey with the followingmobilization of investment for its efficient mining.

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