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Gwalia Mine (Sons of Gwalia Gold Mine), Leonora, Leonora Shire, Western Australia, Australia

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Latitude & Longitude (WGS84): 28° 55' 0'' South , 121° 20' 5'' East
Latitude & Longitude (decimal): -28.91681,121.33498
GeoHash:G#: qdy73pc7m
Owned/operated by:St Barbara Limited
Locality type:Mine
Köppen climate type:BWh : Hot deserts climate


A gold mine. Reopened 1984.

This historic mine is 235 kilometres north of Kalgoorlie and 5 kilometres south of Leonora. Next to the mine is the historic Gwalia township with the 1903 hotel, shopfronts, and miner's cottages. There is also a mining museum right next to the open pit, like any closer it would be in the pit. This has an extensive collection of mining memorabilia, machinery, old buildings, the Herbert Hoover House and head-frame (both pictured) designed by Herbert Hoover. The history of the town will be left to other websites, and we will concentrate on the mine.

The first lease at the site (1896) was applied for by Coolgardie store owner, Thomas Tobias. He named it Sons of Gwalia after his Welsh heritage, 'Gwalia' an ancient word for Wales. In 1897 the lease was sold to George Hall who approached London financiers, Bewick Moreing, to finance the development of a mine. They sent 23 year old engineer, Herbert Hoover, who convinced them to purchase the deposit later in 1897.

Herbert Hoover was to later become the United States 31th President. As mine manager at Sons of Gwalia, he introduced a number of cost saving measures onto the local workforce including single handed work, shift changes, stopped double time on sundays and bonuses for working wet ground. In an effort to side-step union action, he hired Italian immigrants, who to this day have been closely associated with the mine and Gwalia township.

He also oversaw the construction of staff and office buildings on a hill overlooking the mine including the mine managers house now called Hoover House. He lived in it briefly in 1898, before being sent to China by his employers.

Apart from a two year shut-down due to fire in 1921, the mine operated continuously till 1963, and was considered the largest gold producer in Western Australia outside of Kalgoorlie. Due to falling gold prices, the mine closed in 1963, and virtually overnight the Gwalia township declined from 1500 to 40 people. In its 65 years of operations it produced 2 500 000 ounces of gold.

In 1981 a new Sons of Gwalia company was formed by brothers Peter and Chris Lalor, descendants of Eureka Rebellion famed Peter Lalor. Initially the tailings were reworked, then a huge open pit developed, before converting to underground mining in 1999. Initially the company was hugely successful becoming Australia's third largest gold producer. However, unauthorised gold and exchange trading by the chief financial officer saw the company lose 190 million in 2000. The purchase of a number of smaller gold mining companies at inflated prices sealed Sons of Gwalia's fate, and the company went into administration in 2004. In 2008 the mine was sold to St Barbara Ltd, who has continued mining to this day.

The main underground ore shoots at the Sons of Gwalia Mine are Main Lode, West Lode, South Gwalia Series, Hangingwall Series, and South-West Branch. Gwalia has a 500 metre strike length to at least 1750 metres in depth. The open pit above exploited a horseshoe-shaped envelope above the high-grade lodes.

The deposit in this greenstone belt is on the western margins of the broad north-south trending Keith-Kilkenny Tectonic Zone. The deposit is a 120-150 metre thick zone of intensely sheared mafic volcanics with narrow muscovite and to a lesser degree chlorite-tourmaline bands, and wider zones of quartz-carbonate rocks.

Gold is found in partially silicified sericite-muscovite-chlorite schist with disseminated pyrite and traces of chalcopyrite and pyrrhotite, sulphide bearing quartz lenses and stringers in the higher grade zones.


Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


16 valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Actinolite
Formula: ☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Reference: Mock, C. et al (1987), Gold Deposits of Western Australia, BMR, Datafile (MINDEP), Resource Deposit 3, Dept of Primary Industries and Energy, Bur of Mineral Resources Geology and Geophysics, Commonwealth Government of Australia, 1987
Albite
Formula: Na(AlSi3O8)
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003
Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003
Arsenopyrite
Formula: FeAsS
Reference: Mock, C. et al (1987), Gold Deposits of Western Australia, BMR, Datafile (MINDEP), Resource Deposit 3, Dept of Primary Industries and Energy, Bur of Mineral Resources Geology and Geophysics, Commonwealth Government of Australia, 1987
'Basalt'
Reference: Finucane, K. J. (1965). Geology of the Sons of Gwalia gold mine. In Geology of Australian Ore Deposits. 8th Commonwealth Mining and Metallurgy Congress (pp. 95-97).
'Biotite'
Reference: Mock, C. et al (1987), Gold Deposits of Western Australia, BMR, Datafile (MINDEP), Resource Deposit 3, Dept of Primary Industries and Energy, Bur of Mineral Resources Geology and Geophysics, Commonwealth Government of Australia, 1987
Calcite
Formula: CaCO3
Reference: Mock, C. et al (1987), Gold Deposits of Western Australia, BMR, Datafile (MINDEP), Resource Deposit 3, Dept of Primary Industries and Energy, Bur of Mineral Resources Geology and Geophysics, Commonwealth Government of Australia, 1987
Chalcopyrite
Formula: CuFeS2
Reference: http:www.portergeo.com.au/database/mineinfo.asp?mineid=mn760
'Chlorite Group'
Reference: http:www.portergeo.com.au/database/mineinfo.asp?mineid=mn760
Dolomite
Formula: CaMg(CO3)2
Reference: Simpson, E.S. (1948), Minerals of Western Australia, Vol 1, p 463
Galena
Formula: PbS
Reference: Mock, C. et al (1987), Gold Deposits of Western Australia, BMR, Datafile (MINDEP), Resource Deposit 3, Dept of Primary Industries and Energy, Bur of Mineral Resources Geology and Geophysics, Commonwealth Government of Australia, 1987
Gold
Formula: Au
Reference: Mining Annual Review (1985): 41.; Department of Mines (1944) Report of the Department of Mines for the State of Western Australia for the Year 1942.
'commodity:Gold'
Formula: Au
Reference: From USGS MRDS database
'Hornblende'
Reference: Simpson, E.S. (1948), Minerals of Western Australia, Vol 1, p 227
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003; http:www.portergeo.com.au/database/mineinfo.asp?mineid=mn760
Muscovite var: Sericite
Formula: KAl2(AlSi3O10)(OH)2
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003; http:www.portergeo.com.au/database/mineinfo.asp?mineid=mn760
Pyrite
Formula: FeS2
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003
Pyrrhotite
Formula: Fe7S8
Reference: http:www.portergeo.com.au/database/mineinfo.asp?mineid=mn760
Quartz
Formula: SiO2
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003
Quartz var: Chalcedony
Formula: SiO2
Reference: Simpson, E.S. (1948), Minerals of Western Australia, Vol 3, p474
Rutile
Formula: TiO2
Reference: Pasi Eilu (2003) Exploration for orogenic gold deposits. Fennoscandian Exploration and Mining 2003 Rovaniemi, Finland December 2003
'Schist'
Reference: Finucane, K. J. (1965). Geology of the Sons of Gwalia gold mine. In Geology of Australian Ore Deposits. 8th Commonwealth Mining and Metallurgy Congress (pp. 95-97).
Schorl
Formula: Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Reference: Simpson, E.S. (1948), Minerals of Western Australia, Vol 1, p 463
Sphalerite
Formula: ZnS
Reference: Simpson, E.S. (1948), Minerals of Western Australia, Vol 1, p 259
'Tourmaline'
Formula: A(D3)G6(T6O18)(BO3)3X3Z
Reference: http:www.portergeo.com.au/database/mineinfo.asp?mineid=mn760

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
'Arsenopyrite'2.EB.20FeAsS
Chalcopyrite2.CB.10aCuFeS2
Galena2.CD.10PbS
Pyrite2.EB.05aFeS2
Pyrrhotite2.CC.10Fe7S8
Sphalerite2.CB.05aZnS
Group 4 - Oxides and Hydroxides
Quartz4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Rutile4.DB.05TiO2
Group 5 - Nitrates and Carbonates
'Ankerite'5.AB.10Ca(Fe2+,Mg)(CO3)2
'Calcite'5.AB.05CaCO3
Dolomite5.AB.10CaMg(CO3)2
Group 9 - Silicates
'Actinolite'9.DE.10☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
'Albite'9.FA.35Na(AlSi3O8)
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var: Sericite9.EC.15KAl2(AlSi3O10)(OH)2
Schorl9.CK.05Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Unclassified Minerals, Rocks, etc.
'Basalt'-
'Biotite'-
Chlorite Group-
Hornblende-
Schist-
Tourmaline-A(D3)G6(T6O18)(BO3)3X3Z

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Gold1.1.1.1Au
Group 2 - SULFIDES
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
Pyrrhotite2.8.10.1Fe7S8
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 1:2
Arsenopyrite2.12.4.1FeAsS
Pyrite2.12.1.1FeS2
Group 4 - SIMPLE OXIDES
AX2
Rutile4.4.1.1TiO2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
AB(XO3)2
Ankerite14.2.1.2Ca(Fe2+,Mg)(CO3)2
Dolomite14.2.1.1CaMg(CO3)2
Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with borate groups
Schorl61.3.1.10Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Albite76.1.3.1Na(AlSi3O8)
Unclassified Minerals, Rocks, etc.
Actinolite-☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
'Basalt'-
'Biotite'-
'Chlorite Group'-
'Hornblende'-
Muscovite
var: Sericite
-KAl2(AlSi3O10)(OH)2
Quartz
var: Chalcedony
-SiO2
'Schist'-
'Tourmaline'-A(D3)G6(T6O18)(BO3)3X3Z

List of minerals for each chemical element

HHydrogen
H Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
H MuscoviteKAl2(AlSi3O10)(OH)2
H SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
H Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
BBoron
B SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
B TourmalineA(D3)G6(T6O18)(BO3)3X3Z
CCarbon
C AnkeriteCa(Fe2+,Mg)(CO3)2
C CalciteCaCO3
C DolomiteCaMg(CO3)2
OOxygen
O Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
O AlbiteNa(AlSi3O8)
O AnkeriteCa(Fe2+,Mg)(CO3)2
O CalciteCaCO3
O Quartz (var: Chalcedony)SiO2
O DolomiteCaMg(CO3)2
O MuscoviteKAl2(AlSi3O10)(OH)2
O QuartzSiO2
O RutileTiO2
O SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
O TourmalineA(D3)G6(T6O18)(BO3)3X3Z
NaSodium
Na AlbiteNa(AlSi3O8)
Na SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
MgMagnesium
Mg Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Mg AnkeriteCa(Fe2+,Mg)(CO3)2
Mg DolomiteCaMg(CO3)2
AlAluminium
Al AlbiteNa(AlSi3O8)
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Al Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
SiSilicon
Si Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Si AlbiteNa(AlSi3O8)
Si Quartz (var: Chalcedony)SiO2
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si QuartzSiO2
Si SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Si Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
SSulfur
S ArsenopyriteFeAsS
S ChalcopyriteCuFeS2
S GalenaPbS
S PyriteFeS2
S PyrrhotiteFe7S8
S SphaleriteZnS
KPotassium
K MuscoviteKAl2(AlSi3O10)(OH)2
K Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
CaCalcium
Ca Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Ca AnkeriteCa(Fe2+,Mg)(CO3)2
Ca CalciteCaCO3
Ca DolomiteCaMg(CO3)2
TiTitanium
Ti RutileTiO2
FeIron
Fe Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Fe AnkeriteCa(Fe2+,Mg)(CO3)2
Fe ArsenopyriteFeAsS
Fe ChalcopyriteCuFeS2
Fe PyriteFeS2
Fe PyrrhotiteFe7S8
Fe SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
CuCopper
Cu ChalcopyriteCuFeS2
ZnZinc
Zn SphaleriteZnS
AsArsenic
As ArsenopyriteFeAsS
AuGold
Au GoldAu
PbLead
Pb GalenaPbS

Regional 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

Archean
2500 - 4000 Ma



ID: 879350
undivided sedimentary and volcanic rocks 74481

Age: Archean (2500 - 4000 Ma)

Description: Undivided sedimentary (non-volcanic) and felsic volcanic rocks

Comments: sedimentary; igneous volcanic; synthesis of multiple published descriptions

Lithology: Sedimentary; igneous 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). [5]

Neoarchean - Mesoarchean
2500 - 3200 Ma



ID: 3188638
Archean volcanic and intrusive rocks

Age: Archean (2500 - 3200 Ma)

Comments: Yilgarn Craton

Lithology: Greenstone belt; mafic-ultramafic volcanic 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]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Finucane, K. J. (1965). Geology of the Sons of Gwalia gold mine. In Geology of Australian Ore Deposits. 8th Commonwealth Mining and Metallurgy Congress (pp. 95-97).
Mining Annual Review (1985): 41.

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