|Latitude & Longitude (WGS84):||28° 51' 6'' South , 118° 48' 47'' East|
|Latitude & Longitude (decimal):||-28.85170,118.81319|
|Köppen climate type:||BWh : Hot deserts climate|
The Penny West Gold Mine is a small abandoned pit at the southern end of the Youangarra gold belt, and 28 kilometres south of the Youanmi mining centre. It is the only mine in the belt to see modern open pit development. It accessed a high grade vein shoot, discovered in 1990. There are no old workings at the site, the deposit covered by 10 metres of alluvium, and the gold remaining hidden until the discovery. As the site had not been cherry picked by old time mining, the grades of gold recovered were extremely high.
The deposit was discovered by a joint venture consisting of Eastmet Ltd ( a subsidiary of Metana Minerals NL), and Aquarius Minerals NL. In addition to no old workings, there was no evidence of quartz at the surface, or calcrete. RAB drilling in 1990, uncovered significant sulphidic and gossanous quartz with high grade gold, the best result 339 g/t. At lower gold levels, the deposit struck for 400 metres. The deposit trended north, but at one point changed direction to north north-east, and at this point high grade gold was found, 50 g/t was common and localised to 200 g/t. The deposit follows a low north trending 20 metres high ridge. It was mined across 1991 to 1992, the ore processed at the Youanmi plant. It produced 150 000 ounces of gold from 200 000 tonnes of ore at 22 g/t.
The Penny West mine is at the southern extremity of the Sandstone-Youanmi Greenstone Belt. This consists of metamorphosed tholeiitic basalts, intrusives, and minor banded iron formation, porphyries, and felsic pyroclastic rocks. The major regional Youanmi Fault is 3 kilometres to the east of the mine.
The auriferous quartz vein was up to 5 metres thick, and averaged 3 metres, containing weakly sheared metabasalts, with weak development of calcite, ankerite and sericitization. The top 10 metres is gravel/sand, then another 40 metres of saprolite, and below this fresh rock, although oxidation reached 80 metres below the surface in fractures.
Below 50 metres were pods of pyrite, galena, sphalerite and minor chalcopyrite in veins associated with high grade gold. However, some high grade gold was found in quartz with no sulphides.
Late 2012 to early 2013, McVerde Minerals Pty Ltd mined some remnant ore from the north wall of the pit. G. Jorgensen employed by the mine, collected several interesting specimens from the sulphide quartz vein, later studied by Peter Downes at the Western Australian Museum. In the oxidised vuggy part of the quartz veins, some impressive wulfenite crystals up to 8mms in diameter occur, associated with pyromorphite, mottramite, cerussite, and a suite of other species. Of particular interest is bushmakinite, as light green rosettes, and sub-parallel groups of platy crystals up to 2mms wide, encrusting cavities. At the time of writing (2017) it was the first report of the species in Australia, and the third in the world.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
20 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Neoarchean - Mesoarchean|
2500 - 3200 Ma
|Archean intrusive rocks|
Age: Archean (2500 - 3200 Ma)
Comments: Yilgarn Craton
Lithology: Intrusive igneous rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
2500 - 4000 Ma
|ultramafic rocks 74480|
Age: Archean (2500 - 4000 Ma)
Description: Komatiite, peridotite, ultramafic schists, serpentinite, pyroxenite, dunite, amphibolite after pyroxenite; silica cap rock; local u/m pyroclastics; dolerite-textured high-Mg basalt, metapyroxenite and serpentinised peridotite
Comments: igneous ultramafic intrusive; igneous ultramafic volcanic; synthesis of multiple published descriptions
Lithology: Igneous ultramafic intrusive; igneous ultramafic volcanic
Reference: Raymond, O.L., Liu, S., Gallagher, R., Zhang, W., Highet, L.M. Surface Geology of Australia 1:1 million scale dataset 2012 edition. Commonwealth of Australia (Geoscience Australia).