Cauldron Energy Ltd (ASX:CXU) has received an unexpected boost while preparing for ongoing underground drilling at Blackwood Gold Project in Victoria with visible gold observed in an area formerly excavated for access purposes only.
During clearance work in the Tyreconnel Adit following a fall of ground caused by exceptionally wet ground, Cauldron’s team discovered a rise adjacent to the Annie Laurie stope that is believed to have been excavated in the 1990s purely as an access route.
Area of structural complexity
No mining has been undertaken within that specific area, but observations revealed a sharp geological contact between the shale and sandstone.
This coincident area of intense structural complexity is believed to be associated with the Annie Laurie Reef and is where the gold was observed.
The company has carried out channel sampling across this area, with a total of 22 samples collected and submitted for assay and Cauldron believes this may be an exciting new target for future drill testing.
Confidence increased
Cauldron’s executive chairman Simon Youds said: “Our initial plan was to stabilise the Annie Laurie stope and clear the Fall of Ground blocking access to our drill sites. We did not anticipate the discovery of a new, previously unmined, section of the Annie Laurie/Tyrconnel intersection.
"We believe the rise was excavated in the 1990s for access purposes and not specifically related to gold extraction. The visible gold observed, coupled with the beautiful sandstone-shale contact and structurally complex geology, provides an exciting new target for drill testing.
"The sample site is close to existing access, rewarding the company for taking the underground, low community impact, approach. The observation of visible gold further increases our confidence in the remaining mineral potential of these historical mines.”
Underground drilling benefits
Cauldron is continuing to progress drill site access and ground support activities at the historic Blackwood project as drilling from underground and within the existing mining tunnel system provides a significant reduction in risk and cost.
It also allows for greater targeting accuracy of mineralisation extension through exposure of the reef systems within the adits and stopes.
Environmental impacts are also minimised as there is no requirement for surface vegetation clearance, digging of sumps or establishment of tracks and pads.
Focus on Tyreconnel Adit
Work to date has focused on the Tyrconnel Adit that is about 1.5 kilometres in length, trends east-west and intersects many of the north-south orientated reef systems. Multiple drill positions are provided from which to target the down-plunge extensions of up to eight reef structures.
Current, known mineralised trends within the Blackwood Gold Project, overlain on regional geology (ExAct Geoscience, 2020).
Efforts to stabilise the Annie Laurie-Tyrconnel intersection, clear away blockages and reestablish drill site access have been hampered by multiple severe weather systems with resulting state-wide power outages adding to the delays.
Work on schedule
Despite this, reestablishment work has progressed well and is on schedule, keeping within the timeframe initially estimated.
Another benefit of this work is the coincident stabilisation of the surface, thus satisfying one of Cauldron’s initial commitments to preserve and protect the surrounding environment.
Cauldron's ground stabilisation work has been able to help reduce risk of surface subsidence.
Channel samples gathered
Stabilisation and clearance work in the Tyrconnel Adit coincided with the exposure of the top of a ladder rise believed to have been a mine access route.
The walls of this rise revealed an exposed geological contact between sandstone and shale units, as well as an area of high structural complexity.
Historic channel samples near this location show grades of more than 15 g/t gold in a sampling suite that appears to have been terminated in mineralisation. This suggests a hypothetical continuation of gold grades with upwards progression towards, and into, a previously untested section of the Annie Laurie Reef structure.
Geochemical information gleaned from the new suite of channel samples collected by Cauldron may shed additional light on this mineral potential.
Innovative model
"Our team at Blackwood has continued to develop collaborative relationships with the local community. This further builds on our incorporation of innovative sustainability to achieve Cauldron’s unique, holistic, circular economy approach to mining,” Youds continues.
"It is this innovative operational model which allows our current activities to proceed without any impact, to date, to the surrounding surface, environment or local residents. This will be continued as the work program progresses.”