Dart Mining (ASX: DTM) has confirmed multiple mineralised gold structures within its Growlers Hill fault channel after a phase one drill program at its Rushworth project site in Victoria.
The company is now planning to plug two more holes into the prospect and is also launching a phase two campaign at its other promising Rushworth targets within the historic gold region of central Victoria.
Management says its recent six-hole drill program established the structures, which have been historically mined from surface, within the strong north-south Growlers Hill fault channel and at depth. The company’s interpretation is that several structures exist at depth below the historic surface workings in a structural deformation zone.
The zone includes sizeable sub-vertical north-south-oriented structures that interlink with smaller shallow-dipping structures.
Dart says the indications from its assayed drill core of a mineralised structure below or adjacent to known historical workings has encouraged it to pursue further drilling – and the high-grade shoots within the structures will be significant targets.
The company notes that the Growlers Hill reef is likely to be a combination of several structures and there is evidence of carbon-rich shales within the stratigraphic layers, helping to destabilise mineralised fluids and aid in gold deposition.
It is an interesting aside that Dart’s head of exploration Owen Greenberger was an integral part of the team that designed the technical model that led to the renowned nearby Fosterville discovery. The company has found no geological reason to date as to why the early signs at its Rushworth pursuits could not follow suit and throw out a significant find.
Canada’s Agnico Eagle operates Fosterville, a high-grade, low-cost underground gold mine about 50km south-west of Rushworth, with a gold reserve of 1.67 million ounces.
Our target is structurally-hosted high-grade zones similar to the Fosterville mine, 45km away, however Rushworth has its own characteristics and we are building our understanding of these with the ongoing drilling.
Dart Mining chairman James Chirnside
Management has emphasised that it is still at an early stage of exploring the project and its goal of finding a significant orogenic gold system is considered a long-term, but genuine play. It believes its phase one drill program has been a “structural investigative success” and remains confident that the early signs from drilling are positive for the project.
The program comprised 868m drilled, with results of 2.5m at 0.63 grams per tonne gold from 104.5m including 0.5m at 1.9g/t, 3m going 0.42g/t gold from 57m including 0.5m at 1.5g/t and a further hit of 4m at 0.44g/t from 116.7m including 0.35m at 0.99g/t gold.
Dart says mineralisation in the Rushworth region has been dominated by “free gold” in quartz veins hosted within sandstone or shale material. It is particularly interested in areas displaying potential intersections of major structures, which may increase the opportunity for gold deposition.
The company’s phase two drill campaign has also kicked off with 472m of a planned 1620m completed at Star of the West, Henry Horne (formerly Star of the West West) and Shellback. At the Star of the West prospect, three short drillholes were plunged along strike based on previous surface workings.
The Shellback prospect sits between the historically-mined Mouse Reef and West Growlers Reef.
Interestingly, New Holland Mining completed reverse-circulation (RC) drilling at Mouse Reef in 1993 and recorded a result of 3m at 11g/t gold. The result was never followed up and Dart has now just drilled Shellback, targeting an east-west oriented fault.
Henry Horne boasts a stack of historic surface mining features. Dart remains keen to test the target properly and will reassess the best method for further drilling as it believes the scale and nature of the structure is worth pursuing.
Management says encouraging signs have appeared from the program to date, with drill core being processed to submit for assaying. An initial four holes from the phase two program have been logged and sent for assaying and results are pending.
The company considers the Growlers Hill prospect to be a prime target in view of historic mining by old-timers back in the day, with gold grades of more than 200g/t being reported. It featured significant gold production from a northerly-striking quartz vein mined to more than 100m depth, in addition to the adjacent east-west-striking West Growlers reef that is mined to a similar depth.
Dart is only just getting started at Growlers Hill and believes exploration persistence at its project will bring golden rewards to the company.
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