Black Flag Goldfield, Kalgoorlie-Boulder Shire, Western Australia, Australiai

Regional Level Types
Black Flag Goldfield	Ore Field
Kalgoorlie-Boulder Shire	Shire
Western Australia	State
Australia	Country

Located approximately 14 kms south west of Broad Arrow, Shire of Kalgoorlie-Boulder City, Western Australia.

Latitude: -30.53979
Longitude: 121.2367
MGA Zone 51: Northing 6620075 - Easting 330850

Gold was discovered here in 1893 by prospectors Garrity and Clancy (surnames) with financial backing from R.H.Henning. It is about 14 kilometres south-west of Broad Arrow.

The goldfield includes the Mount Pleasant area which is centred on the former Black Flag township. These days it is a 5 kilometre long by 1 kilometre wide maze of open pits, sinuous palaeochannel pits, tailing heaps, processing plants, and machinery sheds. This development has cleared all before it, including any remnants of the Black Flag town, old historic workings, salmon gum woodland, local wildlife etc, and will remain a large area of desolation when the present company has made its money and leaves.

Grants Patch is north-west of the Mount Pleasant mines, and 10 kilometres south-east of Ora Banda. It was also discovered in the 1890's. Unlike Black Flag which saw the early entry of major companies, Grant's Patch largely remained the preserve of the prospector. Since the 1980's, several companies have developed some small pits in the area.

The Black Flag name is believed to have come from a store in the town, that flew a black flag to signify it was open. Its boom days were 1896 to 1897, when some considered it the largest gold mining site in Western Australia. Hundreds of men arrived at the town when the 303 ounce 'Joker' gold nugget from the Devons Consols mine was displayed in Coolgardie. The town boasted eight hotels, post office, police station, hospital, mechanic's hall, bank, recreation area, racecourse, and several more businesses. Numerous large mines surrounded the town, the largest the Black Flag Proprietary with a 50 head battery, and employed 250 men.

Bad management saw many mines go bust. By 1907, the town contained three derelict buildings, and only one mine was operational in the district, and that by a pair of prospectors.

The Ora Banda Greenstone is the dominant rock in the upper levels, intruded by felsic to intermediate porphryry, calc-alkaline lamprophyries and late tectonic granitoids. The sequence includes the Bent Tree Basalt, Victorious Basalt, epiclastic and felsic to intermediate volcaniclastic sedimentary rocks forming the Black Flag Group. The Mt Ellis and Mt Pleasant sills intrude the sequence.

The Mount Pleasant Greenstone sequence is intruded by a small tear shaped composite pluton called the Liberty Granitoid (8 x 10 kms), composed of biotite-hornblende, with minor biotite monzogranite. The main structural features is a series of sub-parallel north north-east striking brittle dextral strike slip fault zones and minor late reverse fault zones. The Mt Pleasant mines are bordered by the regionally significant north north-east trending Black Flag and Royal Standard faults.

Gold is found in the brittle-ductile dextral strike slips, and associated secondary order fault zones within the layered sills, porphyritic and tholeiitic basalts, and adamellite granitoids. Ore shoots are commonly located at fault zone bends and intersections. Gold deposits form primary quartz vein mineralisation, secondary oxide gold, and in the Mt Pleasant area gold in palaeochannels at the contact of saprolite and underlying granite sands.

Historically some of the mines would have produced interesting specimens, especially in combination with sulphides and other material, but was likely all destroyed by the mining process. The Grant's Patch section contains two opalite sites, once popular fossicking areas, but now off limits due to modern gold mining in the area.

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