Fluorite Reef A, Jinka Station, Central Desert Region, Northern Territory, Australiai

Regional Level Types
Fluorite Reef A	- not defined -
Jinka Station	- not defined -
Central Desert Region	Region
Northern Territory	Territory
Australia	Country

North of the Elyuah Range are several substantial reefs and veins of fluorite and barite, adjacent to the Elyuah Syncline. Explored by Central Pacific Minerals NL 1970-1972, who drilled, and dug some small test pits on the reefs. The material was sent to Sydney for analysis, then later at their mobile laboratory at the Bonya Bore camp site.

Central Pacific estimated a total resource for the reefs of 375 920 tonnes averaging 39.66% fluorite. The company provided little detailed information publically for the deposits, although at the time Andrew Browne completed his university thesis on the deposits. Central Pacific name the reefs from A to H, although they indicate the area contains many more fluorite occurrences with only the seven most important named. Reefs A, C, and E are considered the most economically important.

Fluorite to varying degrees is also found in other deposits in the Bonya Hills and Jervois Range areas. It would appear the veins have seen little to no exploration since Central Pacific's time.

Jinka Granite is a medium grained quartz-orthoclase-muscovite granite. This encloses quartz reefs with barite, with less common quartz with fluorite reefs on the northern side of the Elyuah Range, near the Oorabra Rockhole, and west towards the Marshall River in the Molyhil Mine area, and lastly in what Warren describes as the north-east part of a pseudo ring dyke south of the Myponga Range. Fluorite is prevalent in reefs enclosed by the Jinka Granite while barite dominates veins in the Oorabra Arkose.

The layered quartz breccia reefs are found in faults or tension fractures in the Jinka Granite. They contain massive fluorite, with barite, quartz, pyrolusite, chalcedony, hematite, calcite, galena, and thorite. Minor malachite staining may also be present. Numerous cavities and vughs may occur in these quartz-breccia reefs.

The veins form two east-west trending belts, each containing several individuals lodes. The northern belt is 21 kilometres long, with numerous separate lodes, while the southern belt is 8 kilometres long, containing five lodes. Individual reefs are 1.8 to 3 kilometres long, narrow in width, grading up to 57% CaF2 (average 39.66%).

The colourless to purple fluorite forms veinlets and massive lenses in the quartz reefs. Most fluorite is found at the periphery of the reefs, while barite dominates the centre of the reefs.

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References