As part of a strategy to reopen Hillgrove and benefit from strong gold market fundamentals, grab sampling was carried out to estimate the grades of fill remaining in the Sunlight workings.
Gold results up to 14.4 g/t
There were 49 kilograms of samples taken from accessible historic draw points on the 1700 and 1650 levels and assaying returned a weighted average grade of 5.7 g/t gold, 1.8 g/t silver and 0.5% antimony across 20 samples.
The maximum gold grade assayed was 14.4 g/t in draw point 13 on the 1700 Level.
Draw Point 3 at the 1700 Level.
Sunlight vein system has a resource of 680,000 tonnes at 8.0 g/t gold for 175,000 ounces and is open at depth and strike with potential for high-grade gold extensions down plunge and to the southeast.
This is within the overall Hillgrove JORC 2012-compliant resource of 2.8 million tonnes at 5.1 g/t gold and 1.7% antimony for around 460,000 ounces of gold as well as a material JORC 2004-compliant resource.
Potential feed source
There is potential for Sunlight fill to act as a source of feed as Hillgrove transitions from treating the Bakers Creek Waste Stockpile to full restart of underground mining operations.
The Cox’s Lode Decline is connected to the Syndicate Decline and this is only 40 metres from the first designed Sunlight ore drive.
The Sunlight Exploration Decline was recently developed by a previous owner to provide drill platforms at depth to test the down-dip extensions of the Sunlight Vein System.
A long section of the Sunlight workings.
Sunlight Mine was operated from 1878 to 1915 and mined an estimated 200,000 tonnes of ore, of which, an estimated 69,800 tonnes of ore grading 35.7 g/t gold was crushed/processed.
It is believed that the majority of ore that was not selected for processing was predominantly used as fill in the mine.
New England Antimony Mines mined and processed around 6,000 tonnes of Sunlight fill in 2000/2001, with an estimated average grade of 3.7 g/t gold.
The next step is to take a representative sample of the Sunlight fill to conduct metallurgical characterisation test work.
A review of the historical Sunlight mine plans and sections will be undertaken to seek to estimate the amount of fill that is available for mining without any additional development activities.
Cross-cut 4 at the 1650 Level.
Red River is confident that Hillgrove can play an important role as it adds gold to its existing base metals focus.
More than $200 million has been invested at Hillgrove to date and the project includes fully developed and accessible underground workings plus extensive surface infrastructure and equipment, including a 250,000 tonnes per annum capacity processing plant on active care and maintenance.
This comprises a selective flotation circuit capable of producing antimony-gold and refractory gold concentrates, an antimony leach/electrowinning (EW)/refining and casting plant, a gold cyanide leach circuit and gold room and a pressure oxidation circuit.