Drilling at the El Valle mine in northern Spain is expanding high-grade gold mineralization in the recently discovered Sienna zone.
The southernmost of the 13 holes that have penetrated the zone so far is No. 168, which intercepted 53.4 metres grading 9.8 grams gold per tonne. Also encouraging was hole 167, which cut 46.1 metres of 10.2 grams gold. The two holes are separated by 100 metres.
Owner
Meanwhile, the company has revised some previous assays, changing the grade of hole 163 to an uncut value of 33.1 grams gold over a thickness of 41.2 metres; the previous, incorrect value was 13.7 grams per tonne. Also, a 2-metre interval that reportedly assayed more than 40 grams per tonne was found, upon closer inspection, to have graded more than 400 grams per tonne.
Gold mineralization in the Sienna zone occurs in a strongly oxidized brecciated fault gouge at the base of two subparallel thrust faults. The faults trend northeasterly through the deposit, which is associated with the upper plate of the thrust system.
Until the discovery of the Sienna zone, the upper-plate rocks were thought to be barren; now they are believed to have potential for hosting gold mineralization along the structure’s as-yet-untested 6-km length.
Drilling is being carried out north and south of the known mineralization, and Rio says that if the zone proves large enough, the El Valle and Boinas pits could be redesigned as one pit.
The company posted earnings of US$535,700 (or 1 cents per share) during the third quarter, compared with a loss of US$287,800 (nil per share) in the corresponding period last year. Cash operating costs for the recent quarter were US$216 per oz.; gold production, 19,645 oz.
The El Valle mine poured its first gold in February 1998.
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