Mount Pleasant Gold Mine, Peak Hill Goldfield, Meekatharra Shire, Western Australia, Australia
| Latitude & Longitude (WGS84): | 25° 39' 3'' South , 118° 44' 5'' East |
|---|---|
| Latitude & Longitude (decimal): | -25.65090,118.73480 |
| GeoHash: | G#: qekqjfkh9 |
| Locality type: | Mine |
| KΓΆppen climate type: | BWh : Hot deserts climate |
(Map- Google Maps incorrectly locates the former town site of Peak Hill. It is 3 kilometres north-west of the Mount Pleasant Gold Mine)
The site is marked by a shallow small open pit, about 3 kilometres south-east from the former Peak Hill townsite and Main pit.
It was initially mined around 1900, producing a substantial 8,000 tonnes according to the source at 9 g/t Au. Mining resumed in the 1970's and 1980's producing 146,000 tonnes of ore at 3 g/t Au.
The ore zones are flat lying, and emplaced sub-parallel one above the other. The gold is hosted in quartz-carbonate veins, with associated alteration zones of albite, ferriginuous rich chlorite, sericite, carbonate and pyrite, along with zones of black graphitic schist. The veins are vertical or saddle shaped type in anticlinal folds. Geologist studying the deposit called the base the Core Sequence showing in the pit as 55 metres thick. Above this is the Honey Quartzite of ribbon quartz, then the Intermediate Sequence.
The Core Sequence consists of quartz-biotite-carbonate-muscovite, and more minor epidote, hornblende, garnet, magnetite, and pyrite. There was also locally abundant fine zircons and monazite in the biotite rich areas. The graphitic schist is associated with a zone of chlorite-biotite-garnet schist, with albite porphyroblasts, containing inclusions of zircon and monazite.
The Intermediate Sequence is quartz-muscovite schist, with minor plagioclase, biotite, microline, carbonate and chlorite. The lower part of this sequence shows biotite schist with garnet and epidote. Above this is the Mine Sequence of biotite-muscovite, and more minor chlorite, carbonate, amphibolite, garnet and albite schist, and graphite schist. The sequence is 40-50 metres thick.
Above this is the Marker Quartzite of recrystallised quartz mylonite, 1 to 3 metres thick. It contains iron oxide radiating pseudomorphs after acicular crystals as grunerite, and iron oxide pseudomorphs after porphyroblasts as possibly garnet.
The Hanging Wall Sequence is 700 metres thick of muscovite-magnetite-garnet-chlorite, with mafic schist and metabasite. The metabasite is locally garnetiferous with hornblende, plagioclase, quartz, garnet, epidote and titanate.
Commodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
12 valid minerals.
Rock Types Recorded
Select Rock List Type
Alphabetical List Tree DiagramRegional Geology
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 ID: 3186732 | 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. [154] |
| Archean 2500 - 4000 Ma ID: 700170 | Peak Hill Schist Age: Archean (2500 - 4000 Ma) Stratigraphic Name: Peak Hill Schist Description: Quartz sericite schist, quartz muscovite schist, calc-silicate schist, metabasite, mylonite Comments: metasedimentary siliciclastic; metasedimentary carbonate; synthesis of multiple published descriptions Lithology: Metasedimentary siliciclastic; metasedimentary carbonate 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). [5] |
Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License
References
