Astro Resources NL (ASX:ARO) has drilled the first diamond core hole at its Needles Gold Project in Nevada, where it hopes gold will be found deep beneath layers of volcanic rock.
Drilling recently began to test a strong DC/IP chargeability anomaly in the centre of the project that suggests the presence of gold with encouraging early indications.
The company plans to drill up to three inclined core-holes targeting mineralisation at 250 to 500 metres below the surface. A fourth hole may be drilled targeting potential shallower, high-grade epithermal mineralisation as well as deeper Round Mountain type mineralisation beneath the Tomahawk Shaft.
Pyrite mineralisation
The current drill-hole, which has reached 306 metres, has intersected mainly andesitic rocks with propylitic alteration including up to 3-5% disseminated and vein-hosted pyrite, usually accompanied by silicification.
This hydrothermal alteration and the accompanied pyrite mineralisation is consistent with the chargeability anomaly.
The company will conduct interim assays of selected core to determine if gold mineralisation is present.
“It is too early at this stage to confirm whether the core drilled to date contains gold, but the often-strong alteration and significant percentage of pyrite observed, together with interpretation that drilling appears to be progressing towards the heat source, gives us encouragement that we are testing a mineralised system,” Astro chairman Jacob Khouri said.
“We look forward to receiving the preliminary results from fast-tracked assays.”
Geological markers
The concentration of pyrite seems to be increasing down-hole, which indicates that the drilling is moving towards the heat source responsible for the alteration and pyrite mineralisation.
The lack of a chargeable IP response in this unit reflects the lack of sulphides. Aside from pyrite and minor marcasite, initial surveys have not found other sulphide minerals and, in the absence of assays, it is still too early to determine if these rocks contain gold.
Drilling is approaching the edge of the 200-metre chargeability shell at around 330 metres down hole. Chargeability is intensifying, which the company hypothesises will correlate with increased pyrite mineralisation it expects to encounter.