Yamana Resources (YRI-T) has discovered a second high-grade gossanous zone at the Lejano silver prospect in southern Argentina, significantly expanding the known area of mineralization.
Nineteen rock chip samples from the new East Ridge zone graded up to 2,100 grams silver, 8.8 grams gold per tonne and 7% lead. Six gossan samples averaged 699 grams silver, 3.8 grams gold and 3.2% lead.
East Ridge is situated 2 km from the South Ridge zone along an arcuate trend that Yamana geologists believe may represent a Jurassic-aged caldera.
Using Landsat images and field mapping, the company identified a large nest of circular volcanic structures, about 15 km across. The strongest mineralization occurs in volcanic tuffs and breccias along a distinctive ring-shaped fracture zone; this area hosts the North, South and East Ridge zones.
“The whole area is shattered,” said project manager Mel Klohn. “The rock has been both structurally and chemically well-prepared to host orebodies.” Executive Vice-President Richard Walters believes Yamana is dealing with a major system of mineralization.
“We have yet to find its limits,” Walters said.
When the mapping at Lejano is completed, the company intends to launch a second phase of shallow scout drilling before winter consisting of 50 to 60 reverse-circulation holes (totalling 2,000 metres) aimed at the East Ridge and a number of soil-covered areas around North and South Ridge.
The drill is now finishing up at the Goleta and Hombro prospects to the east.
Walters said before a deeper drilling campaign is launched, more geological information must be gathered.
Yamana also plans an induced-polarization (IP) survey to locate deep-lying sulphide targets before any deeper drilling is undertaken.
The company has also begun the legal process of obtaining full mineral title at Lejano, including mining rights, by submitting a Manifestation of Discovery with the Department of Mines. Similar steps are being taken to secure mineral rights at the Bacon prospect. Bacon and Lejano are both part of Yamana’s Santa Cruz project.
Following up on the high-grade drill results from Lejano in January, Yamana submitted 25 check samples to an independent lab for verification. Both labs used fire assays and atomic absorption, and the gold and silver results from the second were within 5% of those from the first, a margin considered acceptable by industry standards. However, lead assays at the second lab were about 10% lower than the first lab, reflecting the inherent difficulty of repeatable lead assays using atomic absorption, Walters said. Yamana plans to recheck the lead values at a third lab using wet chemical assay techniques that should yield more accurate results.
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