Simplified cross section of a copper porphyry system that is generating a mineralized system. The felsic porphyry intrusion is the heat engine that drives mineralizing fluids to various parts of the system.

A copper porphyry system can generate up to six distinct and separate types of ore deposits. The presence of carbonate bedrock is essential for the formation of skarns around the intrusion. A particular copper porphyry does not necessarily generate all of these deposit types, but multiple deposits generally occur in and around the porphyry system.

One type of deposit formed by a copper porphyry system is zinc skarn, which occurs at the outer edges of the mineralized area and typically hosts zinc-lead-silver mineralization. The skarns are poddy, forming mantos (tabular bodies), pods and chimneys or pipes. They range from less than 1,000 tonnes to over 60,000 tonnes in a single body, but cumulatively they can form large tonnages that are mineable from the same mine access. Deposits of several million tonnes have been mined in other skarn districts. The Bolivar mine currently being operated as a pilot mine by Dia Bras is this type of zinc skarn, although at Bolivar the zinc skarn is dominantly a zinc-copper rich and lead- poor skarn because the Bolivar mineralization is copper rich. Grades of the massive sulfide mantos and pods at Bolivar are very high, grading 30-40% zinc and 6-8% copper. Mill feed to Dia Bras’ mill at Malpaso ranges between 12% and 16% combined copper-zinc because low-grade (1-1.5% copper and 4-8% zinc) development rock from drifting of access tunnels to the various high-grade pods is blended with the high-grade material. The Company’s objective is to develop more working faces in higher grade material so that mill feed will be maintained at higher levels.

If the carbonate rock around the intrusion contains a layer of permeable and porous calcic limestone, the mineralizing fluids flowing through it will generate a copper skarn. These skarns are stratabound and can extend laterally for several kilometers. The largest copper skarns known contain up to one billion tonnes of mineralized rock averaging 0.5% copper.

If the carbonate rock surrounding the intrusion contains a layer of permeable and porous magnesian limestone (dolomite or dolostone), a copper-iron skarn is formed. This skarn type can also occur over several kilometers length, either as a single deposit or as multiple deposits in the same stratigraphic layer. The South Bolivar skarn is this type of skarn. The list above shows the range of tonnages and grades of copper-iron deposits just in the Yerington district (Nevada, USA) that were generated by a single porphyry system.

View of an old portal (Mina de Fierro) in the South Bolivar copper-iron skarn. The skarn is about 30 meters thick in this area, which is located between the Bolivar mine and El Gallo. Dia Bras has drilled this skarn over a 250 x 350 meter wide area, and it is open down-dip and along strike. The copper-iron skarn has also been located by drilling below the Level 6 of the Bolivar mine. Old Portal in South Bolivar Cu-Fe Skarn

A view of El Gallo where the South Bolivar copper-iron skarn is exposed along a cliff where secondary copper (malachite, the green stain) occurs within the skarn. The brown disturbed area at the center right view is the edge of the Increible mine, which is a Cananea-type copper breccia pipe. The portal for Mina de Fierro is located over the ridge (behind the house on the top of the ridge) and about 200 meters beyond it. These exposures show the lateral continuity of the copper-iron skarn, which is typical for this type of deposit. The down-dip extent of the skarn has not yet been determined, but the Company is planning a 16,000 meter drilling program during 2006 to continue defining the extent of this deposit. Cu-Fe Mineralization in South Bolivar Skarn

Fluid overpressure that develops in the lateral calcic or magnesian layers, or at the top of the intrusion, forces mineralizing fluids through the overlying rocks causing extensive brecciation (breakage) of the rocks and forms breccia pipes. Where the breccia pipe intersects one of the lateral layers, high-grade low-tonnage copper deposits form. These deposits occur in a doughnut-shaped form around a barren calcite core and can be as small as 100 x 250 meters in size, but still exceedingly profitable. Dia Bras is exploring for a Cananea-type breccia deposit where the Increible breccia pipe intersects the South Bolivar skarn. The two deposits listed occur at the Cananea mine, Sonora, Mexico. At least one other area at Bolivar has been identified as a breccia pipe but is unexplored at this time.

View of the Increible breccia pipe deposit showing the strong relief of the area being explored. Mina Increíble: Cananea-type breccia pipe

The top of the porphyry intrusion can become mineralized as a copper porphyry deposit, where copper mineralization occurs in a large zone of quartz veining and stockwork (cross-cutting quartz veinlets and veins) mineralization. Such a deposit is the heart of the Bolivar mineralizing system but has not been located as of June 2006, and it is a primary goal of the Company to search for this core intrusion during this year.

The Bolivar area is within an extensive trend of copper porphyry deposits.

A compilation of the range of tonnes and grades found in various copper porphyry deposits in this region. These list does not include the tonnes and grades of their associated skarns and breccia pipes.

High-sulfidation gold deposits occur in the upper levels of the volcanic pile associated with the copper porphyry intrusion. The area around the Bolivar mine is eroded deeply enough that the lateral and distal skarns are exposed, and any high-sulfidation gold deposits in the immediate area have been eroded away or are covered by post- mineralization volcanic ash flows.