A new, previously unknown copper occurrence has been discovered in the course of detailed geological mapping by Glenn Diemar, only two kilometres northwest of Copper Hill. The prospect has been named ‘Dash’.
Mineralised float rocks containing malachite were observed over a strike length of 300 metres and follow-up work has located outcrops of strongly silicified, altered volcanic rocks and interbedded limestone intruded by a small granodiorite stock. Pyrite and chalcopyrite is visible as disseminations and in thin veins in the outcropping material with abundant malachite in veins and coating fracture surfaces. Outcrops are small, up to one metre wide. Skarn-related mineralisation may also be present in the sequence.
There are no old workings present in the area; the Copper Hill Induced Polarisation (IP) survey did not extend far enough to reach this area and previous constraints on access prevented detailed soil sampling to be carried out here in the past. GCR’s detailed airborne magnetics does indicate continuation of the pronounced magnetic low extending over 5 kilometres northward, from Vale Head, Lode 3, Copper Hill, Buckley’s Hill through Little Copper Hill and northwards through the Dash Prospect. (See Figure 1 overleaf)
Samples from the first survey were sent for assay and petrography. Mineralised samples returned assays averaging 1.44% copper (range: 0.99% to 2.13% copper).
A petrographic report is in preparation but preliminary findings suggest that the strongly mineralised rocks contain considerable supergene malachite, as well as hematite, chalcocite and traces of azurite. The original rock could have been sedimentary, ranging between limestone and fine-grained sandstone with a volcanic component. Strong alteration to very fine quartz, illite-sericite, carbonate, hematite and sulphides evidently occurred, with subsequent supergene alteration. The other, less well mineralised samples appear to range from limestone through volcaniclastic sandstone to coarse volcanic fragmental rocks of intermediate to mafic composition. Low grade alteration appears to be prevalent, including hydrothermal silicification and hematite development.
The new Dash Prospect will be sampled in more detail (rock and soil) and an IP survey is planned prior to mounting a drilling program.
Planning for a major 4,800-metre deep drilling program at Copper Hill continues, with data review and re-logging of previous holes under way.