Vila Porto Rico
The Vila Porto Rico properties are located in the municipality of Jacareacanga in the State of Pará, immediately east of the Tapajós River, a major north-flowing tributary of the Amazon. Manaus, the nearest principal centre and capital of the adjacent State of Amazonas, is located to the northwest in the heart of the Amazonian territory, at the confluence of the Amazon (Solimões) and Negro Rivers. Manaus has a population of approximately 1.4 million, and enjoyed an extraordinary boom in the latter part of the last century due to the rubber industry.
Prior exploration in the Vila Porto Rico concessions by Rio Tinto Mineral Development (RTMD) in 1995 and 1996 centered on the Ouro Roxo-Nova Brasilia-Cantagalo Shear Zone, and included geological mapping, geochemical soil surveys, and limited geophysical surveys, including Induced Polarization (IP) and magnetometer surveys, auger drilling for geochemical samples, and 4,840 meters of core drilling in 26 drill holes. The cut line grid established by RTMD involved a north-south baseline of 6.4 km with east-west section lines varying from 1.5 to 3 km in length.
Commencing in 2004, Amerix renegotiated the exploration concessions titles and purchase agreement, reviewed the available project technical data and is proceeding with exploration of the concessions at large by geochemical soil surveys and geology of selected mineralized areas and an initial core drilling program involving 4,081 meters of NQ core drilling in 29 holes in the Ouro Roxo North and South areas to add further definition to the identified mineralization in those areas.
Core drilling to date has identified several centres of gold mineralization associated with the Ouro Roxo-Cantagalo Shear Zone. Gold mineralization is interpreted initially to occur in association with quartz injections and accompanying pyrite from an epithermal source. The mineralization appears to occur irregularly along shears and fractures within the central mylonitic zone of the main shear structure.
The Ouro Roxo North (Buriti) zone is associated with a sheared to locally brecciated structure, made up of fragments of encasing rock in a matrix of quartz, calcite, pyrite, chalcopyrite, and sericite, which has accommodated hydrothermal mineralization. The mineralized zones vary for 0.20 to 50.0 meters in thickness and are associated with a mylonitic foliation trending north-south and dip 30° east. The highest gold grades are associated with the brecciated zones and where sulphide concentration is more evident. Breccia zones with sulphide content are also identified which do not contain high gold values. However, generally the sulphide containing breccia zones are indicative of elevated gold content.
The Ouro Roxo South (Pimenteiras) zone indicates that it is also controlled by the shear structure, containing encasing rock fragments in a matrix of quartz, calcite, pyrite, chalcopyrite, and sericite with hydrothermal mineralization. When the breccia cuts the diorite, martite and potassium feldspar are also present. The breccia structure trends north-south and dips 30° east. Interesting gold values also occur outside the breccia zones, but are always associated with fractures and the presence of sulphides.
Numerous smaller veins, to 2 cm thickness, are associated with the main structure and have the same mineralogy and trend as the main vein structure. The encasing rock contains disseminated sulphides, as well as fractures filled by sulphides.
In the garimpeiro operations, the majority of production is from the lateritic and saprolitic material within and especially near-by the footwall contact of the central mylonitic (sheared) zone with an underlying diorite or gabbro. The garimpeiro production and processing operations are elementary, with minimal mechanization and unsophisticated processing. Essentially, material is passed through a relatively short, 2.5 to 3 meter sluice with minimal or no riffles and gold containment is obtained from special gold blankets, from which the concentrate is amalgamated with mercury and retorted to produce a locally saleable product.