Geology
Iberian Pyrite Belt
The Lomero-Poyatos deposit is located in the north-east part of the Spanish/Portuguese (Iberian) pyrite belt which extends about 230 km between Seville in the east (in southern Spain) and the Atlantic coast near Lisbon in the west (in Portugal). The Lomero-Poyatos deposit is located on the northern margin of the pyrite belt.
The Iberian Pyrite Belt is the largest concentration of massive sulphides in the world.
Deposit
The Lomero-Poyatos deposit has an average ENE (075°) strike and dips about 35°N. At the surface there are two separate mineral deposits: Lomero (east) and Poyatos (west) that combine to form a single deposit at depth.
Mineralization
Pyrite is the predominant sulphide, but the sulphide minerals of greatest economic importance are sphalerite, chalcopyrite, tetrahedrite and galena. The massive sulphide and semi-massive sulphide zones at Lomero-Poyatos are significantly enriched in gold. In terms of gold content, the Lomero-Poyatos deposit has the highest gold grades in the IPB with values of 2.0 m at 14.1 g/t Au and 0.55 m at 16.84 g/t Au being returned from CMR/Newmont drill holes in 2007. There is copper-enrichment in the central part of the mine, with some zinc-lead-gold enrichment towards the eastern and western margins of the deposit.