Skarn copper-gold-(cobalt-nickel) deposit.

Located approximately 100 kms south of Cloncurry and is located in the Selwyn Range.

Copper and gold were discovered here by James Elliott in 1889 at Mount Elliott near the site of the future town of Selwyn.

The SWAN and Mount Elliott deposits are located within the Eastern Fold Belt of the Mount Isa Inlier in northwest Queensland, approximately 90 km south of Cloncurry and 20 km north of the Selwyn deposits (#Location: 21° 32'S, 140° 30'E). These two deposits are part of the same mineralised system in which host rock chemistry and structure control mineralisation style within the same low grade envelope. The two deposits are separated by a major steep fault zone.

Four main styles of primary Cu-Au mineralisation are recognised within the Mount Elliott and SWAN deposits: i). The Mount Elliot breccia, ii). the SWAN breccia, iii). banded/replacement mineralisation and iv). late vein hosted mineralisation. These styles are manifested as follows. At Mount Elliott, mineralisation is dominantly within the Mount Elliot breccia, with 0.1 to 20 m wide clasts set in a very coarse-grained, open spaced matrix containing voids up to tens of metres wide. The fragment within the SWAN breccia are much smaller than in the Mt Elliot breccia, and mineralisation at the former is considered to have formed some time after the development of the breccia which created a large porous and chemically suitable trap. Mineralisation permeated, replaced and altered the banded calc-silicate on the eastern margin of the SWAN breccia, forming banded mineralisation of magnetite, hematite-stained albite, chalcopyrite, pyrite, clinopyroxene, actinolite and epidote. Late-stage, 1 to > 200 cm thick veins of coarse-grained calcite, chalcopyrite, pyrite and molybdenite represent an event that crosscuts all of these mineralisation styles (Brown, Lazo, Kirwin and Corlett, 2009).

Mt Elliot mine was earlier (Shiqi Wang and Williams, 2001) described as containing 2.9 Mt @ 3.33% Cu, 1.47 g/t Au, hosted by carbonaceous meta-pelites and amphibolites, occurring in two zones controlled by NW trending, NE dipping brittle faults in a 200 m wide zone of intense post peak metamorphic alteration. It was interpreted as comprising an older, outer, system of albitised meta-sediments (bleached by the loss of biotite and carbonaceous material), over-printed by a "skarn" zone of diopside-hedenbergite veins and replacement features with abundant scapolite, apatite and calcite. Sulphides and magnetite (from outer pyrrhotite-pyrite to chalcopyrite-pyrrhotite-pyrite to chalcopyrite-pyrite-magnetite to magnetite-pyrite±andradite in the core) occur within the skarn, veining and replacing clinopyroxene and intergrowing with calcite.

Brown, Lazo, Kirwin and Corlett (2009) quote a resource at SWAN and Mt Elliot of:

475 Mt @ 0.5% Cu, 0.38 g/t Au at the cut-off grade of 0.25% eCu, still open at depth, including a high grade resource of:
62 Mt @ 1.01% Cu, 0.4 g/t Au at a cut-off of 1.0% eCu.

Localities in this Region

Other Regions, Features and Areas containing this locality

References