Portal Resources Ltd.
TSX VENTURE : PDO

Portal Resources Ltd.

August 04, 2005 09:15 ET

Portal's Drilling Provides Continued Encouragement at Arroyo Verde

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - Aug. 4, 2005) - Portal Resources Ltd. (TSX VENTURE:PDO) is pleased to announce the completion of the second reverse circulation drill hole PO-47, on the large geophysical anomaly in the southern part of the main Arroyo Verde Dome area of the Arroyo Verde Epithermal Gold silver Project, Chubut Province, Patagonia, Argentina.

This geophysical target is a large 2000 meter by 1000 meter anomaly located 500 meters to the south of the Principal Vein area which is characterized by high chargeability and resistivity. This target area is covered by approximately 30-40 meters of gravel.

Hole PO-47 was drilled 150 meters south of hole PO-46A at an inclination of -55 degrees north to a depth of 210 meters. The hole encountered silicified rhyolite with disseminated pyrite and dark quartz stockworks from 89-134 meters and 193-206 meters. The silicified alteration zones are surrounded by broad chlorite alteration from 53-210 meters. A 2 meter epithermal grey quartz-amethyst vein with 5-10 % disseminated sulphides was encountered from 198 to 200 meters at the lower contact of an altered rhyodacite dyke.

Portal Resources is highly encouraged by the intersection of a strong epithermal vein structure on the margin of an intrusive rhyodacite dyke within this large geophysical target area. The drill has been moved to a third location on the same section line 250 meters to the south of hole PO-47 to test the southern portion of the 1000 meter wide geophysical anomaly. A total of seven holes are planned on the South Dome Target area. Assays will be released when received.

Two holes are also planned on the large "Navidad Type" geophysical target located 14 kilometers to the south of the main Arroyo Verde Dome. This "Navidad Type" anomaly is a large area, measuring 2 kilometers by 4 kilometers which is characterized by a strong chargeability high and a resistivity low. The anomaly is outlined at a depth of 100 meters beneath a rhyolite ignimbrite cap which hosts a weak quartz stockwork with geochemically anomalous silver, lead, barite, molybdenum and copper.

Portal continues to be encouraged by the positive results to date from its 4000 meter drilling program which has defined the Principal Vein, a strong epithermal vein system with potential to double in size to the east, as well as additional mineralization associated with the large geophysical targets that are currently being drilled.

Samples for analysis are collected from the site by Alex Stewart Argentina S.A., a subsidiary of the international laboratory Alex Stewart (Assayers) Limited and transported to their laboratory in Mendoza. Samples are analyzed by fire assay for gold and silver. All work on the project is under the direction of Mr. Gary Nordin P.Geo. British Columbia, the designated Qualified Person for the Arroyo Verde project in accordance with National Instrument 43-101.

ON BEHALF OF PORTAL RESOURCES LTD.

Bruce Winfield, President & CEO

The TSX Venture Exchange does not accept responsibility for the adequacy or accuracy of this release.

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