ASX-listed Indonesia-focused explorer Sihayo Gold appears to be homing in on more high-grade mineralisation after the company bagged surface samples yielding up to 36.6 grams per tonne gold and 8.29 per cent copper in North Sumatra.
Notably, of the 57 samples collected, a substantial 35 per cent yielded more than 1 g/t gold, including five between 13.1 g/t and 36.6 g/t gold.
In addition, 33 per cent turned up more than 0.2 per cent copper, including five returning grades ranging between 2.08 and 8.29 per cent copper.
The anomalous results come from surface rock sampling at the Tambang Tinggi prospect found in the northeast corner of the South Block of Sihayo’s overarching PT Sorikmas Mining contract of work. The contract covers two large blocks of exploration ground Sihayo deems highly prospective with its recent drilling in the North Block yielding a 2.1m hit going an impressive 74 g/t gold and 119 g/t silver from 112.8m.
The company said the gold and copper anomalies from the South Block are associated with quartz-sulphide veins and skarns located within a four square kilometre area along the Tambang Tinggi project area.
It said the findings continued to support the South Block’s potential for high-grade gold and copper targets.
Sihayo believes there is insufficient sampling density to comment on the potential size of the prospects, however points to the large peppering of artisanal workings and consistency of anomalies detected in rock chips as encouraging signs supporting the potential for gold and copper discovery.
Interestingly, the South Block contains its own dash of high-grade history, having been mined by the Dutch in the 1930s. The Tambang Tinggi prospect contains the historical Pagaran Siayu underground mine where about 100,000 tonnes of ore was taken out from 1936 to 1939 with reported grades of 6.2 g/t gold, 2.7 g/t silver and 0.24 per cent copper. All significant mining operations ceased coinciding with the start of World War II.
Underground channel sampling by Sihayo in 2006 yielded an array of encouraging results including a 3m intersection going 19.85 g/t gold and 0.85 per cent copper.
The following year, the company completed 11 diamond drill holes for 1153m and produced mineralised intercepts including 0.9m grading 6.27 g/t gold and 0.47 per cent copper from 35.7m and 4m going 3.42 g/t and 0.48 per cent copper from 22m.
Since then, local artisanal miners have intermittently worked the remaining mineralised pillars.
Scout drilling at the prospect was conducted between 2005 and 2011 returning encouraging gold and copper intercepts of 27m at 1.32 g/t gold and 0.11 per cent copper, 31m at 3.42 g/t gold and 0.11 per cent copper and 18m at 5.86 g/t gold.
Late last year Sihayo dusted off its reconnaissance gear and collected encouraging rock chip samples up to 102 g/t gold, 725 g/t silver and 2.31 per cent copper.
Now it plans to further explore the South Block and has applied for permits to work inside areas containing forestry. Importantly, it says some reported samples were taken outside the forestry, with permitting to explore not required.
Additional surface sampling initial results are due this month.
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