Jervois Station, Central Desert Region, Northern Territory, Australiai

Regional Level Types
Jervois Station	- not defined -
Central Desert Region	Region
Northern Territory	Territory
Australia	Country

Jervois Station is a cattle station covering an area of approximately 2,750 Square Kilometres.
The Jervois Range runs through Jervois Station.

The Jervois mining district is 340 kilometres by road north-east of Alice Springs, contained on the Jervois pastoral station. The homestead has an area for bush camping, and what it calls eco-lodges, for passing travellers along the Plenty Highway. A small indigenous community called Orrtipa-Thurra (formerly Bonya and Baikal) is 15 kilometres to the north of the homestead. Access to the area is 17 kilometres east of the Jervois homestead turn-off, heading north along the Lucy Creek track to the eastern edge of the district, then rough station tracks west.

The eastern part of the district contains the north-south Jervois Range, which forms a J-shape, as a steeply north plunging syncline, formed from deformation events. West of this is the Bonya Hills, then further west the Elyuah Range, with plains bordering the Marshall River to the south.

The number of prospects in the district far exceeds those listed on Mindat. Over 70 are recorded, with 49 alone in the Jervois Range, and many more which have not been explored. In fact Petrocarb Exploration in the early 1970's, said it battled to find calc-silicate rock outcrops, that did not contain scheelite to varying degrees, and it appears small copper prospects showing surface secondary mineralisation are widespread throughout.

Mineralisation at the Jervois Range was found in 1929, with the most major mines being Hanlon's Reward, Green Parrot, Marshall-Attutra, Cox's, and Bellbird, showing copper, base metal, and scheelite, along the eastern edge of the syncline, and in its southern nose. A number of scattered mines with similar mineralisation is found in Bonya Schist in the Bonya Hills area, including Bonya, Kings Legend, City of Medina, Samarkand, Xanten, amongst several others.

Both areas were mined spasmodically from the 1930's. This opened the oxidised ore enough to reveal specimens, and often abandoned at short notice leaving abundant secondary copper specimens, but not destroyed by large scale mining due to the small nature of the deposits. Major fluorite-barite veins are found in the Elyuah Range area, with the Molyhil scheelite and
molybdenum mine at the western edge of the district.

From a fossicking perspective the area holds much promise,is under explored, with specimens rarely seen. It is likely to remain that way with active exploration by mining companies over the decades, an indigenous community, and the pastoral station all potentially barring access. Several locations hold abundant secondary copper specimens on the surface. This is mainly malachite staining, some chrysocolla, and minor others. Better specimens are possible. Other base metal specimens are possible, especially chalcopyrite, pyrite, and bornite. Scheelite is also widespread. Crystals of the species are mentioned sometimes in passing in exploration reports.

Garnet of the andradite/grossular variety is widespread, with a few crystal specimens seen, and more noted in exploration company reports, although most of the material is massive. Tourmaline is also common, mainly schorl, mainly massive, but radiating crystals are noted in the reports occasionally. One company report examining specimens noted pink, blue, and dark green elbaite, but no mention is made of crystals. Pegmatites are common in the district, but only mica species and quartz is recorded, and they remain largely un-explored. Some cordierite and andalusite crystals are noted, with massive material again widespread.

Several scattered large scale barite-fluorite veins are found near the Elyuah Range, the fluorite colourless to deep purple. Only massive material is noted, however the veins were only explored by Pacific Central Minerals NL with a few drill holes in the early 1970's. Detailed information on the veins remains unknown. Kornerupine crystals with sapphirine were found in the 1980's, south of Mount Baldwin.

Citrine and smoky quartz crystals have come from the area leased by a fossicker several decades ago, and traded for other specimens, although only general location details are likely attached to them. A basic map found shows several citrine quartz locations in the northern Bonya Hills area, but there is no information on them.

The geology of the area is complex, and space only allows a brief summary. Bonya Schist dominates, as a sequence of muscovite schist with intercalated cordierite schist, sillimanite schist, andalusite schist, fine grained tourmaline rock, calc-silicate rock, pegmatite-quartz rock, and skarn lenses. Mineralisation in the Bonya mines area is in the Kings Legend Amphibolite Member, and schist, amphibolite, quartzite, and microgabbro in the outer part of the Jervois Range J structure.

The Attutra Metagabbro overlies to the east as layered gabbro, dolerite, norite, and magnetite rock. Granites such as the Jervois, Unca, Jinka,
and Xanten Granites intrude other lithologies at various locations, and range in composition from biotite granodiorite to leucogranite. Pegmatite intrusions are often found in the vicinity of copper lodes.

The Neoproterozoic Mopunga Group forms the spine of the Jervois Range, containing the Elyuah Formation (shale, silty sandstone), Grants Bluff Formation (quartz-arenite, quartz-greywacke), Elkedra Formation (siltstone, sandstone, dolostone), overlain by the Cambrian Shadow Group of the Mount Baldwin Formation, and Red Heart Dolomite. This in turn is overlain by middle Cambrian Narpa Group of Thorntonia Limestone, Arthur Creek Formation, and Steamboat Sandstone.

Copper is found in metamorphics associated with basic intrusives; in metamorphics associated with ironstone in schist; as copper staining in quartz-breccia reefs in the Jinka Granite; copper in the Oorabra Arkose of the Elyuah Formation. Scheelite is found in quartz veins in schists; in skarns and calc-silicate rock at the contact with basic intrusives. Fluorite-barite veins are found in the Jinka Granite.

A major structure in the district is the north north-west trending Delny-Mt. Sainthill Fault Zone, a complex, anastromising system of faults and shears. The Mount Baldwin lineament heads south-east from near Mount Baldwin, linking with the Lake Caroline structure to the south-east. More geology will be under individual mines and prospects.

References

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