Corundum
Corundum (Al203), a crystalline form of aluminium oxide with traces of chromium, titanium and iron , should not be confused with carborundum.
Corundum, a crystalline form of aluminium oxide with traces of titanium, chromium and iron, is a mineral that forms on rock. In its natural form it is transparent and clear but is commonly found with different colours caused by impurities. Many specimens are prized as gem stones commonly known as a sapphires or rubies. The name corundum is the Tamil name 'kuruntam' for ruby.
Corundum as an Abrasive
Corundum is very hard and is able to scratch most other minerals and for this reason it is sought after as an abrasive used in sandpapers, emery papers and large machines used for machining metals, wood and plastics. Some emery paper is a mixture of corundum and other substances.
Corundum is found as a mineral in mica, gneiss and schist as well as in some marbles and other low silica rocks and as large crystals in pegmatites. It is commonly found in river and beach sands because of its hardness and resistance to weathering. Abrasive corundum is manufactured synthetically from bauxite.
French Chemists Introduced Synthetic Corundum
French chemist Marc Antoine Gaudin created the first synthetic ruby in 1837 by fusing alumina with chromium (as a pigment), at a high temperature. Another French chemist, Jacques-Joseph Ebelmen, created white sapphires by fusing alumina in boric acid in 1847. The first crystal corundum from which stones were able to be cut was achieved in 1877 by Freil and Frenic. Yet another French chemist, Auguste Victor Louis Verneuil, along with Edmond Fremy, produced the first economically viable synthetic corundum rubies in 1902. A process still called to this day, the “Verneuil Process.”
It is also possible to grow synthetic gem quality corundum by hydrothermal synthesis and flux- growth. Because of the simple ways these gems can be created and because the synthetic product is flawless and larger that those found in nature, along with the large quantities that can be made, the price for such a product has considerably fallen. Synthetic corundum is also used to to make mechanical parts such as:
Corundum is Found in Australia as Natural Rubies and Sapphires in the Following Places:
Corundum sapphires and rubies are the most valued gemstones after diamonds. They have been mined for many thousands of years and have retained a high value despite synthetic corundum being produced since the early 1900's. It is not only the blue sapphire and the red ruby that are mined for their gemstone value but other colours such as green, yellow, and orange are also becoming more and more sought after as valued gems. Sapphires that have a colour other than blue are commonly called “fancy” in the gem stone industry. Non-gem corundum has found uses in the electrical industry and emery has become particularly valued as a hard wearing abrasive.
Australian Mines that produce Bauxite
Gove (NT)
Up to 600 workers employed at the Gove bauxite refinery in the Northern Territory face an uncertain future as Pacific Aluminium suspends alumina production.
Ely (QLD)
The Ely Alcan Queensland Pty Ltd agreement at the Weipa bauxite mine is due to expire in 2041 but an option will give it a further 21 years extension.
Skardon River (QLD)
Gulf Alumina acquired 100 percent of the Skardon River tenement in 2011 from its koalin mining joint partner to develop the mining of bauxite at the site
Weipa (QLD)
The Weipa bauxite mine on the western side of the Cape York Peninsula in northern Queensland is both owned and operated by Rio Tinto Alcan.
Huntly (WA)
The Huntly mine in Western Australia is the largest bauxite mine in the world currently producing about 23 million tonnes of bauxite annually.
Willowdale (WA)
The Willowdale bauxite mine that commenced production in 1984 still processes 10 million tonnes of bauxite a year at the nearby Wagerup Refinery.
Worsley (WA)
The Worsley bauxite mine and alumina refinery in South West Western Australia employs more than 1,800 people and produces 4.6 million tonnes of alumina annually.
South Aurukun (QLD)
The South Aurukun bauxite tenements on the Cape York Peninsula in Far North Queensland are held by Gulf Alumina.
Marchinbar Island (NSW)
The Marchinbar Island bauxite deposit in far north Northern Territory could be mined to satisfy a growing demand from China in the near future.
Kwinana Refinery (WA)
The Kwinana refinery in WA employs around 1,000 direct employees with 60 percent living in the nearby towns of Rockingham, Cockburn and Kwinana.
Wagerup Refinery (WA)
The Alcoa owned Wagerup alumina refinery in W.A. has received governmental approval to lift alumina production from 2.6 to 2.65 million tonnes annually.
Pinjarra Alumina Refinery (WA)
The Pinjarra alumina refinery, near Mandurah south of Perth, is an important part of Alcoa's three refinery system in Western Australia.
Portland Aluminium Smelter (VIC)
The Portland Aluminium smelter in western Victoria, a joint venture operation between Alcoa, CITIC and Marubeni, caters solely to the Asian market.
Felicitas (WA)
The Felicitas bauxite project in Western Australia contains a bauxite resource of 220 million tonnes that will give it a life of mine of 25 years
South Of Embley (QLD)
Despite Rio Tinto placing its South of Embley bauxite project in Cape York, Queensland, on hold for 18 months it still considers it a 'good project.'
Bauxite Hills (QLD)
The Bauxite Hills Project on the Cape York Peninsula in Queensland is hoping to take advantage of an expected increase in the demand for Alumina.
Bald Hill (TAS)
Australian Bauxite Limited's Bald Hill mine, in Tasmania, is to start production in December, 2014. It is the first new bauxite mine in Australia, for over 35 years.
Urquhart Point (QLD)
The Urquhart Point Heavy Mineral Sands Project in Cape York in Far North Queensland is expected to begin production in mid-2015.
Amrun (QLD)
The Amrun bauxite project in far north Queensland, that was previously known as the 'South of Embley' project has been approved for development and expected to be in production by 2019.
