exploration & operations
Sulphide

The sulphide deposits of Centralny and Severny lie immediately beneath the oxide deposits (Figure 4). Due to the relatively high grades and good ore zone continuity, these have been the focus of attention for some time, initially by Goscomgeology, and in the 1990’s by Lonrho. Lonrho included both Centralny and Severny sulphides in their 1995 Feasibility Study, although the former was to be mined by open pit.

 

Although not as well understood as the near surface oxide mineralisation, the sulphides have been explored from a number of shafts, the deepest being Amantaytau Severny No 10 Shaft, developed to a depth of 359m below surface. More recently, sulphide mineralisation has been uncovered in the base of Pit 1 at Centralny where the oxide mineralisation is contiguous with the deeper sulphide ores. In contrast, Severny is a blind Ore Zone with minimal oxide ore.

Figure 4: Schematic Longitudinal Section through the Amantaytau Deposit
Figure 4: Schematic Longitudinal Section through the Amantaytau Deposit

 

The Centralny deposit has been tested to a down dip extent of up to 480m.  Severny has generally been tested to a depth of 640m below surface, although one drillhole intersected high grade mineralisation 870m below surface (Figure 5). A total of 282,914m plus 1,070m of Lonrho core drilling had been undertaken at Centralny and Severny prior to Oxus’ programme of 5 holes (406.7m), three of which penetrated into the sulphide zone. The potential to extend the resources down plunge is significant and this will be the focus of exploration in the forthcoming years.

Figure 5: Section Though Drillhole 1767a
Figure 5: Section Though Drillhole 1767a

 

CSMA Consultants Limited ((now Wardell Armstrong International (WAI)) produced a Pre-feasibility Study of the sulphide Ore Zones in 2000 which was followed up in 2002 by a Technical Audit Report of the Amantaytau sulphide deposits which considered an updated geostatistical model of the Ore Zones. WAI was commissioned in 2004 by Oxus Gold plc (Oxus) to provide a Feasibility Study for the Amantaytau underground project to develop the Severny and Centralny sulphide gold Ore Zones which form the basis of Oxus’ proposed underground sulphide mining operations. The Feasibility Study was completed in September 2005.

 

Mineral Resources and Ore Reserves and the forward strategy are discussed in the “Geology and Exploration Report for Year Ended 30th June 2007” and the section on “Ore Reserves and Mineral Resources for Year Ended June 2007” which are both on this website. Details on the proposed mining and metallurgical plan for the sulphides and the balance of oxides throughout the lease area are also discussed in the “Annual Report for the Year ended 30th June 2007” which is also on this website.