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Barite

Barite (barium sulphate, BaSO4), the only commercial source of barium and barium compounds, is a relatively soft, inert mineral with a high SG (Specific Gravity) in the range of 4.2-4.5. Approximately 90% of world production is used as a weighting agent in drilling mud for oil and gas wells where the high SG assists in containing pressures and preventing blowouts. It is used as a heavy filler in special paper, rubber, paint and plastics applications. Its radiation absorbing properties are used in special concretes and in barium meals for medical X-ray examinations. Barium compounds are used in ceramic glazes and to enhance the brilliance and clarity of optical and TV glass. World production is ~6 Mt/year, one-half of which comes from China. South Australia, with a current production of ~10 000 t/year, is Australia's largest producer (Fig.1, Production Figures).

Over 160 barite deposits or occurrences have been documented in South Australia, with a total recorded production of 690 000 t. All but a few of these are of the open-fracture infill type hosted by Adelaide Geosyncline rocks in the Mount Lofty and Flinders Ranges. Deposits generally comprise steeply dipping tabular bodies up to 5 m wide which crosscut the enclosing sediments and metasediments.

Flinders Ranges

Many deposits in the Flinders Ranges are spatially related to diapirs, either as veins infilling fractures along steeply dipping diapir - country rock contacts or radiating from diapirs. Over 400 000 t of barite have been produced from the dozen or so individual deposits associated with the Oraparinna Diapir including the only South Australian mines in current production at Oraparinna and Dunbar (Fig. 2, Barite Deposits in South Australia).

barite_oraparinna.jpg (11869 bytes)
Roberts lode No.2 level entrance portal, Oraparinna Mine.

Oraparinna

Production commenced at Oraparinna, 500 km north of Adelaide, in 1940. Normandy Industrial Minerals, which operated the deposit from 1984, transferred the mine to Unimin Australia Ltd in 2000, continuing the mine's long history as Australia's largest supplier of industrial-grade barite. The mine, comprising seven underground levels, works a system of 1-2 m wide veins which have developed in tensional fractures within Adelaidean Wilpena Group sediments in a graben structure extending from the northeastern corner of the Oraparinna Diapir. Ore is trucked 160 km to a treatment plant at Quorn where three industrial grades of barite - A, Standard and B - depending on colour, are produced for use in surface coatings, plastics fillers and mould coatings at Olympic Dam. Some A and Standard grade material is trucked to Gillman in suburban Adelaide for fine milling. 2002 production of 5248 tonnes is the largest since 1996.

Dunbar

This deposit, formerly known as "Linke's Lode", is ~15 km southwest of the Oraparinna Mine and is worked by an open cut on a 30 m wide subparallel vein system ~500 m in length. Individual veins are up to 9 m wide. The ore is enclosed in a raft of Adelaidean sediments within the Oraparinna Diapir. Most Dunbar ore is used in the production of oil-drilling grades of barite, but some is used to feed a magnetic separation plant at Quorn which produces a super-white AA industrial grade. Production has been historically high since 1997, totalling 11254 tonnes in 2002.

Other Deposits

Other smaller barite deposits which have been worked in the Flinders Ranges include those at Appealinna, Artipena, Carey Hill, Martin's Well and Mount John in the Blinman area, Mount Coffin (10 km east of Leigh Creek) and Mount James (30 km northwest of Beltana).

Mount Lofty Ranges

Numerous mines have been worked in the past but are now abandoned, such as at Julia Creek (72 km northeast of Adelaide) where 10 500 t of barite were produced from a number of small mines between 1925 and 1974.

The largest deposits were located in the Brachina Formation in an area 3 km south of Noarlunga. A total of 57 000 t were produced from four main workings between 1918 and 1961.

Small tonnages of high-quality barite were obtained from Woodside during 1978.

Other barite mines which have been worked out or abandoned include those near Athelstone, Uraidla, Prairie and Birdwood; two of the oldest mines are at Aldgate and Williamstown.

Olary District

Large, low-grade deposits in the Olary district occur at the same stratigraphic level within a banded iron formation in metamorphic rocks of the Willyama Supergroup. The deposits are conformable with bedding of the country rock and are considered to be of sedimentary origin. The barite is of drilling grade due to the presence of silica and iron oxide. The largest deposits are at Mount Mulga (21 km north of Olary) which produced 14 000 t of oil drilling grade between 1962 and 1980, and Walparuta (11 km northeast of Weekeroo Station) which produced 54 t between 1946 and 1954. Other occurrences are at Dome Rock, Waukaloo, Ameroo Hill and Meningie Well.

Eyre Peninsula

Mount Whyalla barite mine, 24 km northwest of Whyalla, was selectively worked over a distance of 1 km from a series of vertical lenses in the Pandurra Formation. Similar veins occur in the Moonabie Formation at Mount Laura overlooking Whyalla, and in the Burkitt Granite and Corunna Conglomerate at Corunna, 15 km northwest of Iron Knob.

A deposit of high-grade barite crops out adjacent to the manganese deposits on the floor of Pernatty Lagoon near the western shore. It forms a rise elevated 0.3 m above the general lake level over an area 6-12 m wide and is traceable for 500 m as a succession of patches forming a long, narrow lode.

 

Additional Reading

Hiern, M.N, 1976. Barite South Australia. In: Knight, C.L. (Ed.), Economic geology of Australia and Papua New Guinea, 4, Industrial minerals and rocks. Australasian Institute of Mining and Metallurgy. Monograph Series, 8:27-30.

McCallum, W.S., 1990. Oraparinna barite deposits. In: Hughes, F.E. (Ed.), Geology of the mineral deposits of Australia and Papua New Guinea. Australasian Institute of Mining and Metallurgy. Monograph Series, 14:1159-1161.

Valentine, J.T., 1989. Industrial and non metallic minerals operations in South Australia. South Australia. Department of Mines and Energy. Report Book, 89/74:3-11. (pdf file ~ 490kb)