Pilgangoora pegmatites, Pilgangoora, East Pilbara Shire, Western Australia, Australiai

Regional Level Types
Pilgangoora pegmatites	Pegmatite Field
Pilgangoora	Property
East Pilbara Shire	Shire
Western Australia	State
Australia	Country

The north Pilbara region contains at least 125 pegmatites in 25 groupings. They are a diverse collection mineralogical speaking.

The Pilgangoora pegmatite swarm can be found in the central west section of the area, near the old gold processing plant site. It represents the second largest hard rock lithium resource in the world. The largest is Greenbushes, also in Western Australia. By the time you read this, there could be a very large lithium mine developed at the location, considering the lithium boom presently taking place.

Economic lithium resources are controlled by three groupings of leases, and companies. If a mine should develop, these will have to be combined at some stage. The main deposit is held by Pilbara Minerals, mainly directly south of the Pilgangoora gold mine. (Resource Measured Indicated and Inferred 128.6 Mt @ 1.22% Li2O and 138 ppm Ta2O5-2016)

Altura Mining holds large reserves immediately west of the Pilbara Mining tenements. Altura Mining has currently (2016) secured an offtake agreement with Chinese batteries material producer Lionenergy, and recently completed a feasibility study mapping out the mining, processing, logistics and support infrastructure required to commence mining and processing of spodumene at Pilgangoora, timing plans to develop the Pilgangoora Lithium project to coincide with the lithium battery boom.

Further pegmatite containing leases are found immediately south held by various companies in recent times. Other companies have outlying leases, hoping to cash into the boom.

The Pilgangoora pegmatites are in a belt 1.5 kilometre wide by 8 kilometres long trending north-south. The pegmatites have intruded into north-south trending faults within the Archaean metamorphic (lava, cherts and pyroclastics) rocks of the Warrawoona Group. The pegmatites are long narrow veins of spodumene and lepodolite with cleavelandite units showing either quartz-spodumene-albite-microcline; quartz-microcline-albite-muscovite; or quartz-muscovite-microcline-cassiterite-plagioclase. The first is the source of tantalum ore containing manganotantalite, columbite, tapiolite and microlite. Beryl and spessartine garnet is seen occasionally.

Pictures of the pegmatites are not greatly impressive, often covered by alluvium. The main lithium bearing mineral is spodumene, which forms large crystals, often beige coloured (iron staining?). Decent specimens of various species for collections is likely, and also likely to never become available due to the large scale mining planned.

The pegmatites are hosted by the regional East Strelley Greenstone Belt, 10 kilometres wide, consisting of steep dipping mafic, ultamafic volcanic, and amphibolite rocks. There has been repeated folding and faulting of this, and is sandwiched between the Carlindi Batholith to the east and north-west, and Cleland Supersuite to the south-west.

The greenstone has been intruded by a swarm of north-south trending, east dipping zoned pegmatites, in an area 8 kilometres long by 1.5 kilometres wide. Individual pegmatites range up to 1250 metres long, averaging 100 to 200 metres, 1 to 8 metres wide. They are irregular dyke like forms, often splayed, forked or with poor terminations.

The spodumene forms large crystals, frequently though altered to lepidolite or other mica species. The spodumene crystals are aligned perpendicular to the contacts, as well as some random orientations. They are unusual in not having the typical 'pull apart' structures typical of spodumene.

Non lithium ore is columbite, tantalite and cassiterite, and minor tapiolite and microlite. Ore ranges from manganotantalite to manganocolumbite to ferrocolumbite, of which one site in the area is the type locality. Cassiterite is most common on the Hanging Wall side, while tantalite-columbite is most common on the Footwall side. There is a close association between the spodumene, tantalite and tin minerals.

Historically it is these ore minerals, which have been mined to a limited degree, mainly by prospecting parties. Several lease applications were found across the 1930's to 1950's, although locations in the area of each is uncertain.

William James Lynas 1930 and 1931; Frederick Thelemann from Port Hedland
No. 100 30 acres 1930, and 102 48 acres 1931; Thomas Henry Atwood, William Edward Griffiths of Marble Bar No. 133 300 acres; J.H. Collett, F.L. Freeman, W.E. Griffiths No. 160 & 161 300 & 299 acres 1941;
William Edward Griffiths, Noami Rosenthal, Lindsay Kenneth Rosenthal, Jessie Isabell Zeffert, Julius Harold Zeffert No. 166 299 acres 1945 and No. 174 & 175 100 acres each 1947; tenders advertised for leases 291, 326, 327 and 329 in 1954 for the Northern Development and Mining Company in liquidation; John Christian Pelle of Nullagine No. 228 (identical to 217) 1950 & No. 231 120 acres 1951.

Early 1950's, the Northern Development and Mining Co, came to a mining arrangement with Ronald William McLeod and Ernie Mitchell, who inturn employed a party of local aboriginals to mine tantalite-columbite. This company went into liquidation, leaving McLeod and his employees unpaid. Who had the rights to the ore mined, and left at the site in drums, was the subject of court cases. In turn, William Griffiths, who was active in the area at the time, claimed the ore had been taken illegally from his lease. The Perron brothers were also mining in the area at the time for tantalite, with a processing plant closer to Port Hedland on the Turner River.

Small operations for tantalum continued until 1978, producing a total of 33.3 tonnes of tantalite, and 13.1 tonnes of tantalite-columbite. Pilgan Mining conducted large scale operations from 1978 to 1982, then Pilgangoora Mining Venture 1992 to 1996, altogether obtaining 140 tonnes of tantalite concentrate.

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