Vancouver – Greystar Resources (GSL-T, GYSLF-O, GSL-L) has delivered an updated resource estimate for its large Angostura gold-silver deposit in northeastern Colombia.
The study sees a boost in the indicated resource estimate, now at 166.4 million tonnes averaging 1.31 grams gold per tonne and 6 grams silver per tonne, largely from an upgrade of prior resources classified as inferred. Indicated resources host 6.98 million contained ozs. of gold and 31 million ozs. of silver. Roughly one-fifth of the gold is in oxide mineralization with the remainder as sulphide. Cut-off grades of 0.4 gram gold and 0.55 gram gold were used for oxide and sulphide mineralization respectively.
Inferred resources stand at 83.3 million tonnes grading 1.57 grams gold and 7 grams silver to tally about 4.2 million contained ozs. of gold (about one-seventh as oxide and the remainder as sulphide).
The updated resource estimate is based on drilling of almost 162,000 metres in 505 holes and reviews a total of 11.2 million contained ozs. of gold in both the categories, an almost 9% increase over the 10.3 million contained ozs. tabled in mid-2005. The resource study will serve as a basis for an independent scoping study underway on the Angostura deposit.
Greystar is contemplating driving a crosscut in the underground workings at Angostura to allow for further infill drilling by underground rigs and to evaluate the high-grade La Alta area. With 25-metre spacing, the company believes delineation of higher-grade gold zones may boost the average indicated resource grade.
Angostura is a high sulphidation gold-silver deposit with mineralization predominantly hosted in porphyritic monzonites and in lesser amount within gneisses. Mineralization is structurally controlled, occurring in vein systems.
Greystar envisions an initial heap-leaching operation at the project, targeting the upper oxide zone, to be followed by development of the deeper sulphide zones.
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