|Latitude & Longitude (WGS84):||32° 6' 14'' South , 119° 46' 51'' East|
|Latitude & Longitude (decimal):||-32.10394,119.78110|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
The Bounty gold anomalies were discovered in 1985 by Aztec Exploration Limited after re-studying drill cores taken searching for nickel. The mine operated from 1988 to 2002, with Bounty, West Bounty and North Bounty pits which were developed over the strongest anomalies. The mine is 115 kilometres south south-east of Southern Cross. The mine closed when Aztec hit financial difficulties, when gold recovery rates were not to expectation.
The mine is located in a southern extension of the Archaean Southern Cross Greenstone Belt. This belt is dominated by tholeiitic basalt, with lesser sandstone, siltstone and chert. Ultramafic rocks include komatiite altered to chlorite schist and serpentinized dunites. There are also some banded iron formations. A series of east striking lower Proterozoic gabbroic dykes cut the belt.
At Bounty, gold is found in a narrow belt called the Bounty Horizon. This is composed of banded iron formation related Fe rich amphibolites, and some associated siliceous and pelitic rocks. Dolerite flanks the zone to the west, and high Mg basalt to the east.
Weathering at Bounty reaches 40 metres. It consists of variable Fe rich clays, lateritic fragments, black Fe rich nodules, pale grey sandy clays, bleached saprolite and yellow-brown loose sands.
Gold mineralization is found in a steeply dipping shear system, with near vertically west dipping banded iron formation and chert. There is a strong association between the gold and the underlying banded iron formation and chert. Gold occurs in zones of quartz-sulphide-carbonate alterations, at an average grade of 5 g/t over a 20 metre wide near surface zone.
The sources here give far more information than will fit on Mindat. They focus on economic mineralisation, and a visit to the waste dumps at the mine by the writer would indicate there are more species than listed here.
JORC confirmed resources for the Bounty Main mine is 3.3 Mt of ore at 3.69 g/t yielding 319 000 ounces of gold. The mine produced 1.3 million ounces of gold during its 12 year life.
The Bounty Horizon is a sheared amphibolite iron formation and chert rich beds (50% each) 15 to 30 metres thick, dipping steeply west. The iron rich beds contain grunerite-ferroactinolite, magnetite-biotite, magnetite-grunerite-ferroactinolite or rarely magnetite-plagioclase. Thin iron rich pelitic interbeds are less common and contain biotite-almandine-hornblende-grunerite. The chert rich beds contain granoblastic quartz, and some magnetite, grunerite and ferroactinolite. Hedenbergite forms parallel bedding bands and cross cutting bands.
Pyrrhotite dominates the Bounty Horizon, with up to 60% of rock in the strongly deformed zones. It forms disseminated replacement to magnetite rich bands, vein fillings, and as a matrix to breccia. In addition there is minor pyrite, marcasite, arsenopyrite, chalcopyrite and sphalerite in the veins. Pyrite and marcasite are abundant in the upper oxidised levels but minor at depth.
Spodumene and muscovite rich pegmatites intrude the Bounty Horizon. The regionally major Binneringie Dyke cuts the Bounty Deposit, and has oxidised pyrrhotite to magnetite within 100 metres of it.
Gold is mainly found in the strongly deformed areas of the Bounty Horizon near the Hanging Wall, and in one area near the Footwall. Three types of veins occur in the former (1) quartz-calcite-hedenbergite-garnet (2) pyrrhotite rich veins and matrix breccia (3) quartz with visible gold. The quartz-gold veins are 3 to 20 cms thick and extend from 1 to 10 metres. The gold is found associated with quartz, calcite, and hedenbergite, with disseminated pyrrhotite, pentlandite, molybdenite and chalcopyrite. Veins containing quartz, actinolite, pyrrhotite, apatite, biotite and clinozoisite do not contain visible gold.
The area of Footwall with gold shows quartz veins with visible gold, and associated with haloes of hedenbergite and pyrrhotite. Gold rich breccias contain mineral clasts of hedenbergite, calcite, plagioclase, quartz, actinolite, and blue-green hornblende, with minor biotite and apatite.
Between the Hanging Wall and strongly deformed areas of the Bounty Horizon is a chlorite zone, showing as smooth shiny black rock. Some quartz is found in this as aggregates, rod shaped and steep plunging with minor pyrite, and pyrrhotite, (and graphite at the southern end of the deposit).
The Hanging Wall is fine to coarse grained subhedral hornblende after pyroxene (40-60%), plagioclase, some actinolite and variable amounts of biotite. There is minor pyroxenitic and tremolite rich layers towards the lower contact with the Bounty Horizon.
A zone of intense veining occurs within the Footwall rocks, adjacent to the Bounty Horizon, ranging from 1 to several metres with veins forming 50% of the rocks. The veins are quartz-pyrite-actinolite-pyrrhotite in variable proportions, strongly deformed or recrystallised and folded. Undeformed veins contain clinopyroxene with inclusions of calcite, euhedral epidote, and an outer rim of clinozoisite and some quartz.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
24 valid minerals.
Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
- Igneous rock
- Sedimentary rock and sediment
- Metamorphic rock
- Unclassifed rock
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
|metamorphosed ultramafic rocks 74286|
Age: Archean (2500 - 4000 Ma)
Description: Metamorphosed komatiite, pyroxenite, chlorite-tremolite schist, talc-chlorite schist, anthophyllite-tremolite-talc rock; olivine-cummingtonite schist; talc-carbonate-tremolite-chlorite rock, serpentinite; amphibole schist after pyroxenite
Comments: igneous ultramafic volcanic; meta-igneous ultramafic intrusive; synthesis of multiple published descriptions
Lithology: Igneous ultramafic volcanic; meta-igneous ultramafic intrusive
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 crystalline metamorphic 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.