Lagunas Norte differs from many other large high- sulphidation epithermal gold deposits of the Andes in that a majority of the known resource is contained within Cretaceous siliciclastic sedimentary rocks, and a relatively small portion is within the Tertiary volcanic sequence that is the primary host elsewhere (e.g., Yanacocha, Pierina). The main host rock sequence at Lagunas Norte consists of quartz sandstones and subordinate interlayered mudstone, siltstone, and carbon-rich siltstone, correlated with the Lower Cretaceous Chimú Formation (Lewis, 2002).

The Lagunas Norte mineralization occurs in the southeast portion of the Alto Chicama property. The mineralization is finely disseminated and is hosted mostly by siliclastic sedimentary strata.

The mineralization within the present pit extends for approximately two kilometres in the north-northwest direction by approximately two kilometres in the east-northeast direction and for more than 200 m vertically.

Mineralization is the result of multiple volcanic and hydrothermal events. It is hosted in both the Tertiary volcanics of the Calipuy Group and the underlying Cretaceous sedimentary rocks of the Chimú Formation. The alteration associated with the mineralization is typical of a highsulphidation epithermal environment, characterized by silica (SiO 2 ), surrounded by alunite [KAl3(SO4)2(OH)6], dickite [Al2Si2O5(OH)4] and pyrophyllite [Al2Si4O10(OH)2]. Trace elements typically associated with these deposits include copper, arsenic, barium, bismuth, zinc, lead, and variable amounts of mercury (Silberman and Berger, 1985). The deposit has very low concentrations of carbonate minerals or other potentially acid neutralizing minerals.

There are both stratigraphic and structural controls on the mineralization. Mineralizing fluids ascended along the main fault systems and migrated laterally along stratigraphic contacts in both the sedimentary and volcanic rocks. At least two stages of sulphide mineralization are recognized. The sulphide assemblage comprises mainly pyrite (FeS2) with lesser amounts of enargite (Cu3AsS4) and occurs as replacement structures, veins, and disseminations in volcanic breccias and highly fractured and locally brecciated Chimú sandstones. Most of the mineralization (75%) occurs as oxide material, with approximately 25% occurring as sulphide material. Supergene oxidation has altered a large part of the sulphide assemblage to iron oxides and, to a lesser extent, sulphates. The extent of this oxidation ranges from a few metres to more than 300 m below surface. Approximately 90% of the mineralization is contained within the Chimú sediments and the balance is hosted in the Calipuy volcanic rocks.

The gold grade times thickness contours clearly show the Lagunas Norte deposit is approximately two kilometres by one kilometre wide.

Mine operations are considered a typical truck/shovel open pit operation with a fleet of 184 tonne payload rigid frame haul trucks combined with diesel powered face shovel excavators and front end loaders as the primary loading equipment. Haul trucks are also utilized to transport ROM ore directly to the HLF, along with crushed ore to the HLF for stacking. A fleet of large diesel powered blast hole rigs are employed for production drilling of blast patterns.

Pit Dimensions: 2.5 km long x 1.5 km wide x 170 m deep (no backfill) and Typical Bench Height - 10m.

The recovery process used at Lagunas Norte is a two-stage conventional crushing circuit, followed by heap leaching, and a Merrill Crowe zinc cementation plant and CIC for recovery of the precious metals. The major components of the process are primary crushing, secondary crushing, heap leaching, recovery plant, refinery, and water discharge treatment plant.

The crushing circuit was originally designed to crush 42,000 tpd, but the capacity is permitted to 63,000 tpd. Historically, it was determined that the gold recovery from heap leaching at Lagunas Norte is not overly dependent on crush size, so the size has been increased over time to allow more material to be processed through the crushing circuit. The crushed ore is conveyed to a 2,000 tonne live capacity stockpile, from which it is fed to the secondary crushers. From the secondary crusher, the ore is loaded into haul trucks that transport it to the leach pad. Lime is added to the trucks to raise the pH of the leach sol ........