Gold in Low Sulphidation Veins and Stockworks
Available for Joint Venture
The Piedra Negra Project is located approximately 40 Km North of Cerro Vanguardia gold mine in the center of the Deseado Massif of Santa Cruz Province. It is accessed in around 30 minutes from the Tres Cerros Hotel on 25 Km of good unpaved road which crosses the project.
Magna Terra Minerals Inc.
Magna Terra Minerals Inc. has 100% control, through a leasing agreement with a private individual, of the Piedra Negra M.D.s and Puyutano Cateo which constitute 20,000 Hectares with the project occupying a small corner of the Piedra Negr II M.D. as well as a small corner of the Puyutano Cateo. Magna Terra Minerals Inc. also controls the Covadonga M.D. which is adjacent to this project. The area of interest is divided for convenience into 4 zones which, from North to South, are the “Domos de Puyutano”, “Vetas Hermanas”, “Vetas Ocultas” and “Domos de Piedra Negra”. The vein and stockwork field varies in width from 250 m to 700 m and has a strike length of 2.4 Km from north to south.
Geology: The Piedra Negra project is characterized by Au bearing, low sulphidation veins and stockworks, hosted in andesitic flows and rhyolitic domes of the Bajo Pobre and Chon Aike Formations respectively. The four mineralized zones vary significantly in character in terms of geology and mineralization. The Vetas Hermanas zone includes the site of the initial discovery and is characterized 900 meters of low sulphidation, banded, crustiform and cockade texture veins which are hosted largely in andesite flows. The veins in this zone vary in strike between 350° to 20° and are intermittent, with sampling being based on interpolation of outcrops into areas of sub crop and float. The 113 rock chip and saw cut samples reported so far have an average Au grade of 0.58 ppm. A weak trace element signature includes Pb 31 ppm, As 14 ppm and average Hg of 104 ppb with the latter being calculated from the 47 samples available with Hg cool vapor analysis.
The Domo Puyutano Zone, to the north of the Vetas Hermanas, is characterized by low sulphidation veins in a rhyolitic dome complex. Of the 24 rock chip samples taken in this zone, 15 were above detection in Au. The average Au in the zone is 0.53 ppm which is similar to the Vetas Hermanas zone but with a geochimal signature of average Pb 388 ppm, average As 29 ppm and Hg anomalies averaging 24400 ppb with the latter being calculated form only 13 samples where results are available. We note that the high Au values are restricted to N-S striking veins in the flank of the dome and are probably associated with the Vetas Hermanas zone whereas the high Hg anomalies occur mostly in an ENE striking vein within the dome, suggesting the presence of an overprinting system.
The Vetas Ocultas Zone, to the south of the Vetas Hermanas, is physically and stratigraphically higher than the Vetas Hermanas Zone. Veins occur in the form of float and sub-crop which we interpret as having cut the underlying andesites below the tuffs and volcanic breccias in which they occur. Au grade in this zone is spotty with many samples below detection and the 41 rock chip samples reporting an average Au grade of 0.096 ppm. Average Pb is 47 ppm but As and Hg are weak in this zone reporting averages of 3 ppm and 38 ppb respectively.
The Domos de Piedra Negra Zone has grown to an East – West extension of 280 meters of anomalous Au in veins and stockworks hosted in Rhyolitic dome material. Whilst the extension of mineralization is generally E-W and N-S in this zone, individual veins strike WNW, which is more typical of the orientation of mineralization in other parts of the massif. Of the 77 samples reported in this zone the average Au grade is 0.179 ppm and this is accompanied by 84 ppm Pb, 13 ppm As and 225 ppb Hg with the Hg being calculated from the 38 samples where cool vapor analysis was available.
We are currently continuing with sampling and mapping on the project and plan to follow this with ground magnetic and IP programs.