- 01Javelin completes 1,000m Coogee West drill hole.
- 02Mafic rocks may explain magnetic anomaly; assays pending.
- 03Gold-copper mineralisation unconfirmed.
Javelin Minerals (ASX: JAV) has completed a 1,000-metre deep diamond drill hole at Coogee West near Kalgoorlie, encountering a previously unrecognised sequence of mafic rocks within a large magnetic target beneath Lake Lefroy.
The hole—the second deep test of major intrusive targets at the company’s Coogee gold-copper project, following drilling at Coogee North—brings the government-supported program to the geological interpretation stage.
While several thick dolerite units may account for the magnetic response that prompted drilling, laboratory assays have not yet been completed and the presence of economically significant gold or copper mineralisation remains unconfirmed.
Geological logging is finished, with core cutting and sampling to follow before Javelin combines assay results and downhole magnetic measurements to reassess the two targets.
Unexpected Rocks at Depth
The Coogee West hole passed through the felsic and intermediate volcanic rocks and diorite intrusions familiar from other parts of Coogee before revealing mafic volcanic and intrusive units not previously recognised within the project.
Several of the dolerites showed substantial deformation, including brittle structures associated with quartz-carbonate veins and chlorite, epidote, and potassium feldspar alteration, alongside occasional quartz-magnetite veins.
These observations provide geological detail about the deep target, but visual logging alone cannot establish whether the newly encountered rocks carry material concentrations of gold or copper.
Javelin collected magnetic susceptibility readings while drilling and will feed them into its existing three-dimensional magnetic modelling to test whether the intersected mafic rocks explain the modelled anomaly.
That distinction is important because confirming the source of the magnetic signal would refine the geological interpretation without necessarily establishing an orebody.
Similar Magnetic Signature
Coogee West was selected partly because its magnetic signature resembles the Coogee North anomaly, which sits beneath previously identified gold-copper mineralisation.
At Coogee West, transported sediments associated with Lake Lefroy obscure the underlying rocks and limit the usefulness of surface geochemical sampling, leaving historical shallow drilling as a key source of evidence.
That drilling outlined a bedrock gold anomaly extending roughly 900m by 500m, with bottom-of-hole samples returning grades of up to 1.38 grams per tonne of gold.
Before the current diamond program, neither of the large modelled geophysical features had been tested by deep drilling directed at its interpreted source.
The newly completed holes therefore provide the first direct geological information at depth beneath targets previously defined principally through geophysics and shallower exploration.
Gold-Copper Resource
The broader Coogee project already hosts a mineral resource estimate of 3.6 million tonnes at 1.08g/t gold for approximately 127,000 ounces, alongside a copper resource of about 1Mt at 0.41% copper containing 4,122 tonnes.
Those existing estimates relate to the established deposit and must be kept separate from the deeper intrusive targets, where no new assay results or mineral resource additions have been reported.
Coogee was previously mined by Ramelius Resources (ASX: RMS) during 2013 and 2014, while significant parts of the wider tenement have received relatively limited exploration compared with the resource area.
The deep drilling program has been co-funded by the Western Australian Government’s Exploration Incentive Scheme, enabling Javelin to investigate both Coogee North and Coogee West.
Once sampling, assays, and magnetic interpretation are complete, the combined geological and geophysical evidence will guide Javelin’s decision on whether further exploration of the deeper targets is warranted.
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