Lake MacDonnell is a

salt lake A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...

on western

Eyre Peninsula The Eyre Peninsula is a triangular peninsula in South Australia. It is bounded by the Spencer Gulf on the east, the Great Australian Bight on the west, and the Gawler Ranges to the north. Originally called Eyre’s Peninsula, it was named aft ...

near the

Nullarbor Plain The Nullarbor Plain ( ; Latin: feminine of , 'no', and , 'tree') is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its ...

. The closest town is

Penong __NOTOC__ Penong ( ) is a town and locality on the Nullarbor Plain, in the far west of the state of South Australia located about north-west of the state capital of Adelaide. With no settlements between it and Border Village on the border with ...

, to the north. It is the site of a former salt mine, now the largest

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...

mine in Australia on the largest gypsum deposit in the southern hemisphere. Salt is still mined but as a secondary product.

Ore body

The ore body consists of

calcrete Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, ...

coastal dunes of the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

Bridgewater Formation in a northwest-trending depression. The gypsum formed during the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

period. The gypsum deposit has a one-metre layer of gypsarenite containing 93 percent gypsum (

calcium sulphate Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Pari ...

). Below that is a layer of

selenite Selenite may refer to: Substances containing selenium *A selenium-containing anion or ionic compound with the SeO32− anion: **Selenite (ion), anion is a selenium oxoanion with the chemical formula SeO32− ***Selenous acid, the conjugate acid, w ...

containing 94-96% calcium sulphate. The deposit may contain as much as 500-700 million tonnes over an area of .

Mine

Gypsum has been mined at Lake MacDonnell since 1919. Since 1984 the mine has been owned by Gypsum Resources Australia (GRA), which is owned 50% each by USG

Boral Boral Limited is Australia's largest building and construction materials supplier, with market-leading positions in quarries, cement, concrete and asphalt. Boral is actively pursuing a decarbonisation strategy through recycling of demolition ma ...

(itself a 50–50 joint venture of

USG Corporation USG Corporation, also known as United States Gypsum Corporation, is an American company which manufactures construction materials, most notably drywall and joint compound. The company is the largest distributor of wallboard in the United States ...

and Boral) and

CSR Limited CSR may refer to: Biology * Central serous retinopathy, a visual impairment * Cheyne–Stokes respiration, an abnormal respiration pattern * Child sex ratio, ratio between female and male births * Class switch recombination, a process that chan ...

. Production is about 3.5 million tonnes (3.4 million long tons) per year. Gypsum is mined using bulldozers and excavators. It is stockpiled for several years to allow salt to leach out from natural rainfall. It is then loaded onto trains using front-end loaders.

Railway

Gypsum is transported on an isolated railway operated by

Aurizon Aurizon ( ) is a freight rail transport company in Australia, formerly named QR National. it was the world’s largest rail transporter of coal from mine to port. Formerly a Queensland Government-owned company, it was privatised and floated o ...

to the port of Thevenard. Normally three trains run each weekday, with fewer at weekends. It is further stockpiled at Thevenard, then loaded on ships to

Glebe Island Glebe Island was a major port facility in Sydney Harbour and, in association with the adjacent White Bay facility, was the primary receiving venue for imported cars and dry bulk goods in the region until 2008. It is surrounded by White, Johnston ...

Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...

for further processing. The railway's terminus is named Kevin – deriving from the

Hundred of Kevin 100 or one hundred (Roman numeral: C) is the natural number following 99 and preceding 101. In medieval contexts, it may be described as the short hundred or five score in order to differentiate the English and Germanic use of "hundred" to de ...

, which was named after the adopted son of the 19th century South Australian politician

Charles Kingston Charles Cameron Kingston (22 October 1850 – 11 May 1908) was an Australian politician. From 1893 to 1899 he was a radical liberal Premier of South Australia, occupying this office with the support of Labor, which in the House of Assembly wa ...

. Originally part of the Port Lincoln Division of the

South Australian Railways South Australian Railways (SAR) was the statutory corporation through which the Government of South Australia built and operated railways in South Australia from 1854 until March 1978, when its non-urban railways were incorporated into Austr ...

, the "station", comprising only a small corrugated steel waiting shed, was very rarely used because of the lack of nearby settlement.

References

{{reflist MacDonnell Mines in South Australia Gypsum mines in Australia

Ore body

Mine

Railway

See also

References