Barrick works to upgrade Diablillos project in Argentina — Company shares indirect interest in gold-silver project with Pacific Rim Mining

In an attempt to increase the resource of the Oculto gold-silver zone, Barrick Gold (ABX-T) has completed an 8,000-Metre drill program on the Diablillos property in the northwestern Argentine province of Salta.

The property is under option to a company in which Barrick owns a 70% indirect interest, with Pacific Rim Mining (PFG-V) owning the balance. To retain its interest, Barrick is required to spend US$10.5 million over a 4-year period, and, each year thereafter, a further US$4 million, until a production decision is reached.

A final property payment of US$3.75 million is due July 1, 1997.

Situated near the capital city of Salta, the project is accessible by road.

It comprises 3,600 ha of moderate relief in an area of widespread hydrothermal alteration at an elevation of about 4,000 metres.

The Oculto is the most advanced of four known gold-bearing epithermal zones on the property. Sub-horizontal in dimension, the structure is an oxidized deposit of high-sulphidation gold-silver mineralization.

In the early 1990s, BHP Minerals spent US$1.4 million exploring the property, completing a 55-hole, 6,800-Metre drill program.

Following limited drilling in 1994 by Pacific Rim, consulting geologist James Mustard estimated the total resource at Diablillos to be 5.1 million tonnes grading 2.4 grams gold and 236.6 grams silver per tonne. Oculto alone was estimated to contain 4 million tonnes grading 2.1 grams gold and 256 grams silver.

Pacific Rim struck its deal with Barrick in 1995, and, in mid-1996, the latter began subjecting the Oculto to comprehensive drilling.

In its 1996 annual report, Barrick stated that “an 8,000-Metre drill program on the Diablillos property continues to meet with encouraging results.” The most recent drilling by Barrick has confirmed the continuity of the northeast-striking Oculto zone, while extending it 150 metres to the northeast and locally expanding the width to 250 metres.

The Oculto is roughly estimated by Pacific Rim to measure 600 metres along strike, with a width averaging 200 metres and an average thickness of 50 metres. Mineralization remains open along strike.

Assay results were recently reported from 29 of the 37 latest reverse-Circulation drill holes, up to hole 97-69. Mineralized intervals ranged from a low-grade 5 metres averaging 0.01 gram gold and 100 grams silver per tonne in hole 97-32 to a high-grade 17 metres of 6.27 grams gold and 15.6 grams silver in hole 97-63. Better-Than-Average thicknesses were demonstrated by holes 97-48 (78 metres averaging 1.03 grams gold and 156.5 grams silver), 97-50 (150 metres of 0.87 gram gold and 243.8 grams silver) and 97-56 (88 metres of 1.19 grams gold and 193.5 grams silver).

Geophysical surveys by Barrick indicate the controlling fault structure of the Oculto zone continues to the northeast under a windblown sand cover.

Geophysics also identified a parallel structure, 500 metres south of Oculto, as a potential target.

Meanwhile, Pacific Rim is set to begin an initial 8-To-10-hole, 2,000-Metre, widely spaced drill program on Cerro Blanco, which adjoins the Diablillos property. The main target is a porphyry prospect, where surface sampling identified an anomalous 600-by-200-Metre area. Twenty samples from this area averaged 0.28 gram gold. The company speculates that the mineralization could be leached at surface, suggesting the potential for higher grades at depth.