An induced polarisation survey at the 100%-owned project, about 25km west of Oberon, has identified an approximately 800m-long Central target as a priority for Legacy Minerals (ASX:LGM) .
The north-north-west trending zone is modelled from about 100m below surface and coincides with a previously identified soil geochemistry anomaly.
That overlap gives Legacy a specific subsurface target to investigate beneath an area where earlier fieldwork found copper-bearing rocks and elevated gold, silver and other metals.
The Central target returned modelled chargeability of up to 45 millivolts per volt, while the North-West target showed a response above 40mV/V at a modelled depth of approximately 200m. While such responses may reflect disseminated sulphides or alteration, chargeability is not diagnostic of mineralisation.
The survey covered five lines, with receiver arrays totalling 7800m. One line returned chargeability below 3mV/V throughout and generated no target but helped distinguish the stronger responses elsewhere.
CEO and managing director Christopher Byrne said it was hard to ask for better than these three clear, untested copper targets.
“Our strategy at Rockley has always been to determine whether the high-grade copper and gold we see at the surface reflects a larger system at depth,” he said.
“This is the first time we have an extremely high-conviction geophysical response, up 45mV/V over an 800m strike length, coincident with highly anomalous surface geochemistry.”
Byrne added that the three targets had not been drill tested, and Legacy’s focus was now to work towards doing just that.
The Crystal Hill magnetic low target area with 3D inverted chargeability isoshells over highlight rock chip assays, historic workings and geology. Pic: LGM
Historical reconnaissance rock-chip sampling returned individual assay maxima of 9.3% copper, 3.9g/t gold and 415g/t silver across the area.
An earlier first-pass soil survey collected 570 samples on a 200m by 100m grid across 12km2. It outlined elevated gold, arsenic, molybdenum and antimony, with less coherent copper, lead and zinc anomalism.
Historical exploration included a small number of reconnaissance holes less than 14m deep more than 25 years ago but did not test the three newly defined targets.
Rockley broadens Legacy’s exploration pipeline while work continues at flagship Mt Carrington, where an optimised scoping study is assessing a larger project scale following July’s resource update.
The company also has a new study underway assessing scandium alongside the existing nickel and cobalt resource at its NiCo Young project in Central NSW.
For Rockley, the next task is to integrate the two-dimensional and three-dimensional survey models with mapping, structural interpretation and soil and rock-chip geochemistry. Drill testing of the three targets is under consideration, subject to drill planning, landholder access, statutory approvals and funding.
