|Latitude & Longitude (WGS84):||29° 44' 47'' South , 121° 2' 58'' East|
|Latitude & Longitude (decimal):||-29.74648,121.04952|
|Köppen climate type:||BWh : Hot deserts climate|
The Yunndaga is 6 kilometres south of Menzies, and borders the west side of the railway line. The site presently displays an open pit, with a large rehabilitated tailings plateau to the south-west, and far smaller tailings heap to the north-east next to the railway line.
The Octagon Syndicate was able to peg several leases during the initial goldrush on Menzies in 1894. One of these was the Royal group. Andy Wilson was the initial mine manager, and Paddy Lynch the underground manager.
In October 1895, the Octagon Syndicate was floated in London as the Menzies Consolidated Gold Mining Company. 6 x 24 acres leases. GML 5531Z, 5532Z and 5535Z. Ex Great Extended Hustler mine manager at Bendigo, William Weeklay, was employed as mine manager, with J. Allen underground manager and Latham Watson metallurgist.
225 000 pounds was raised by shareholders, although they had to wait until 1914 and 1915 to see a dividend. The company made a marginal profit each year to keep going, but these two dividends amounting to 22 400 pounds is all that shareholders would see. The mine operated under the Menzies Consolidated company from 1895 until it closed in 1927. It was the mainstay of the district during this period, employing up to 150 men. A 20 head battery was on the site.
W. Callagher in August 1910 almost had his ear torn off from a fall of rock in the underground workings. Years before he had sued Fred Merton for a half share of the Merton's Reward Gold Mine, but lost the case. His brother, Chas. Callagher was a hotel keeper in Menzies. George Nestler (28) died in December 1914, when he became caught in a driving belt, and flung around the shafting in the battery. In March 1912, Frederick Darcy, went to work underground and was found dead later at the bottom of a shaft, but what happened remains a mystery.
During the Menzies Consolidated period the mine had produced 515 822 tonnes of ore for 272 226 ounces of gold at 16 g/t. The workings had reached a depth of 2200 feet. The next couple of years two prospectors, Halbert and Randall (surnames) sent some small crushings through the battery, being the dregs the company had left behind.
In 1933, the leases are owned by James Semmens Allen. He sells it to mining speculator Charles de Bernales, and his Australian Machinery and Investment Company. Some diamond drilling took place but little else.
While little mining had taken place after 1927, the large pile of sands from the former battery remained a tempting target. It was a mixed combination of fine sands, coarse sands, and slimes, acid in nature, and proved difficult to treat. A company tried in the early 1940's using the expensive decantation process, and abandoned the project after spending 13 000 pounds.
Patrick William Maher and Gordon David Wishart investigated processing the material in 1947. Sydney investors promised vast sums of money to construct a processing plant but it amounted to nought.
In 1995 to 1998, the whole site was destroyed by an open pit development by Paddington Gold Ltd, who carted the ore to their processing plant near Broad Arrow. 650 000 tonnes of ore was extracted for 75 779 ounces of gold at 2.5 g/t.
The deposit is hosted in amphibolite rocks, along the margin of the Yunndaga sedimentary package, and consists of quartz veins with an envelope. The lode trends north-south, dips 70 degrees west and plunges south-west. Pyrite and arsenopyrite are dominant, with some chalcopyrite, galena, and sphalerite. Historically, it is the largest ore body mined in the Menzies area.
Mineralisation forms discrete shoots, hosted along the sheared and altered contact between a mafic amphibolite sequence to the east, and an amphibolite felsic volcaniclastics and shale to the west.
Mineralisation is hosted within biotite-quartz-chlorite alteration zones on the contact mentioned above. Several porphyry felsic units are also present. The deposit is situated in the highest strain point in the Menzies shear zone.
Several late sinistral east-west faults cross the north end of the pit. Gold is hosted in quartz bodies, parallel to the stratigraphy and sinistral shear bands. Quartz stringer veins, with quartz-sericite are also found within the sedimentary units. Above the deposit is 60 metres of regolith.
The principal ore shoot mined historically was called the Princess May, 120 metres long, 1 metre thick above 300 metres, and 2 metres thick below 300 metres in depth. There are a series of narrower and less continuous shoots between the Princess May and the Hanging Wall, along the strike of the Yunndaga Shear, shown along the full length of the open cut. The most significant of these areas is where the pit was deepened to 110 metres, 500 metres north of the Princess May shoot.
JORC Resources remaining are 830 000 tonnes of ore at 2.42 g/t yielding 64 527 ounces of gold.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
10 valid minerals.
Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
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
2500 - 4000 Ma
Age: Archean (2500 - 4000 Ma)
Comments: meta-igneous mafic; synthesis of multiple published descriptions
Lithology: Meta-igneous mafic
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). 
|Neoarchean - Mesoarchean|
2500 - 3200 Ma
|Archean volcanic rocks|
Age: Archean (2500 - 3200 Ma)
Comments: Yilgarn Craton
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.