Northern Orion and BHP define zone in N.W. Argentina

Drilling in the Filo Amarillo area of the Agua Rica project in northwestern Argentina continues to broaden a newly discovered zone of high-grade copper.

Situated in Catamarca province, Agua Rica is a major porphyry copper deposit, with significant gold, silver and molybdenum values.

The property is held 70% by BHP Copper and 30% by Northern Orion Explorations (NNO-T).

The partners are in the midst of a 25,000-metre program of infill and stepout drilling on three contiguous areas of higher-grade mineralization: Mi Vida, Quebrada Minas and Trampeadero. The drilling is part of a US$45-million program designed to advance the project to completion of a final feasibility study in 1998.

The deposit extends for more than 2,000 metres east to west and up to 1,200 metres north to south. Based on 103 holes completed to the end of 1996, BHP calculated a sulphide resource of 802 million tonnes grading 0.61% copper and 0.24 gram gold, plus 3.17 grams silver and 0.034% moly, using a cutoff grade of 0.4% copper. This is equivalent to a contained resource of 10.8 billion lbs. copper, 6.2 million oz. gold, 82 million oz. silver and 601 million lbs. moly.

When the cutoff is lowered to 0.2% copper, the sulphide resource is estimated at 1.7 billion tonnes grading 0.44% copper and 0.19 gram gold, plus 3.01 grams silver and 0.028% moly, equivalent to 16.2 billion lbs. copper, 10.2 million oz. gold, 166 million oz. silver and 1.1 billion lbs. moly.

An overlying leached cap is estimated to contain 89 million tonnes grading 0.41 gram gold, or 1.2 million oz., based on a 0.25-gram cutoff.

The newly discovered higher-grade copper zone in the Filo Amarillo area is 183 metres southwest of the Trampeadero area. The latest hole, No. 145, encountered 32 metres averaging 1.05% copper and 0.1 gram gold, plus 15.65 grams silver and 0.085% moly.

Hole 145 is only the fourth hole from the Filo Amarillo area to be released. Results from the other three holes include:

* 25.9 metres averaging 1.61% copper and 0.23 gram gold, plus 1.87 grams silver and 0.044% moly, in hole 135;

* 64 metres averaging 1.41% copper and 0.19 gram gold, plus 5.32 grams silver and 0.11% moly, in hole 134; and

* 29.3 metres averaging 0.29% copper and 0.13 gram gold, plus 2.38 grams silver and 0.031% moly, in hole 132.

Northern Orion says the drilling has extended the Filo Amarillo zone for a total length of more than 500 metres.

Meanwhile, infill drilling in the Mi Vida and Trampeadero areas has returned the following selected results:

* 248 metres averaging 1.08% copper and 0.22 gram gold, plus 2.26 grams silver and 0.038% moly, in hole 138;

* 410 metres averaging 0.66% copper and 0.35 gram gold, plus 8.62 grams silver and 0.034% moly (including a 164-metre interval grading 0.99% copper and 0.28 gram gold, plus 2 grams silver and 0.053% moly), in hole 141; * 362 metres averaging 0.67% copper and 0.29 gram gold, plus 1.95 grams silver and 0.026% moly (including a 120-metre interval grading 1.22% copper and 0.46 gram gold, plus 2.61 grams silver and 0.018% moly), in hole 142; and * 52 metres averaging 0.99% copper and 0.26 gram gold, plus 1.81 grams silver and 0.045% moly, in hole 143.