ASX-listed Indonesia gold explorer Sihayo Gold has clocked up more encouraging gold intersections from a diamond drilling program at its brownfields Sihayo gold project in North Sumatra. The pick of the assays from the latest seven holes at the Sihayo-2 prospect for which the Brisbane-based company received results were 5m grading an average 1.17 grams per tonne gold from 25m, 3m going at 0.79 g/t from 4m and 4m at 0.76 g/t from 16m. Other gold sniffs included 14m at 0.56 g/t from 16m depth, 19m at 0.45 g/t from 54m and 9m at 0.45 g/t from 4m.
They come after other recent notable drill intercepts from Sihayo-2 including 8.4m at 2.56 g/t from 47m, 9.8m at 1.77 g/t from 77m, 24.8m at 1.09 g/t from 52m and 8m at 1.32 g/t from 96m.
Sihayo has now completed 20 of the planned 30 diamond holes totalling about 3,000m at the Sihayo-2 near-mine auriferous jasperoid target.
According to management, the drill hits continue to hint at the potential for a satellite, low-strip-ratio gold deposit with favourable metallurgical characteristics within cooee of the proposed Sihayo gold processing plant and keystone Sihayo-1 and Sambung resources.
Sihayo Gold Executive Chairman Colin Moorhead said: “The results are in line with our aims for the Sihayo-2 exploration program and support the presence of near-surface mineralisation located close to the existing Sihayo starter project resource. Further investigations are underway to assess whether the occurrence is potentially economic as early mill feed.”
Sihayo-2 sits about 500m-to-1km from the main Sihayo-1 gold deposit on an interpreted north-west strike projection.
Sihayo Gold says the prospect contains a strong concentration of jasperoid boulders and outcrops occurring along a narrow north-west-south-east oriented ridgeline and down the eastern slope into a deeply eroded valley, coincident with the proposed northern waste dump location.
The area also takes in untested gold-arsenic-antimony soil and coincident induced polarisation chargeability anomalies generated in earlier exploration programs.
The company says that at this stage well developed gold mineralisation at Sihayo-2 is apparent over some 250m of strike length and has up to 10m-15m true thickness along the ridgeline on the western side of the prospect.
It appears to be fault-bounded on the western edge and open along a north-east trending dip-slope where the mineralisation and prospective host rocks are partly eroded.
Concurrent with the diamond drilling at Sihayo-2, a program of geotechnical and hydrogeological drilling designed to contribute to optimisation and design studies on the Sihayo starter project is in progress.
Sihayo Gold tabled a robust definitive feasibility study or “DFS” on its proposed Sihayo gold mining and processing “starter project” development more than a year ago that featured a forecast EBITDA averaging about US$93 million a year over an initial life of mine of eight years based on average gold production of about 79,375 ounces per annum.
The combined measured, indicated and inferred mineral resource estimate for Sihayo-1 and the nearby Sambung deposit currently stands at 24 million tonnes at an average grade of 2 g/t for 1.5 million ounces of contained gold.
Within those resource numbers, Sihayo-1 and Sambung host proved and probable ore reserves of 12.5Mt at 2.1 g/t for 840,000 ounces of contained gold, with Sihayo-1 accounting for 11Mt at 2.1 g/t for 750,000 ounces of the reserves.
Pre-production capital costs of construction were estimated at about US$144 million in the DFS.
Average all-in sustaining costs of production were put at an impressive US$709 an ounce and development capital payback at 25 months.
Sihayo Gold’s prime drilling targets – Sihayo-1, Sihayo-2, Sambung, Hutabargot Julu and Sihayo-3, 4 and 5 – lie within the Sihayo gold belt that consists of two sub-parallel mineralised trends identified in past exploration work.
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By Matt Birney
