Corundum Australia

This Article is Under Construction



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Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?



Corundum
Australia
Al₂O₃

Corundum is a common and attractive mineral that are or has been mined as a gemstone or as an industrial product at various localities around the world. The corundum article is therefore split into a multiple articles, one for each continent as follows:

Corundum main article
Corundum Africa
Corundum Americas
Corundum Asia
Corundum Australia
Corundum Europe and Russia

As of now, only the Corundum Americas has reached the "the first draft" level.

Right now this is an unstructured collection of photos from the database. I am confident that the images does not reflect the best Australian corundums. I am sure that there must several profilic localities that has no photo uploaded to Mindat, and I hope some of the many Australian contributors to Mindat can help me in choosing the right localities to include in the article, and hopefully also some better photos.


Corundum
Australia
New South Wales, Gough Co., Glen Innes, Reddestone Creek




Corundum
Australia
New South Wales, Gough Co.,Inverell district

Corundum up to 25mm crystal	© M.Goodwin 2012

Corundum
Australia
Northern Territory, Harts Ranges (Hartz Ranges), Inkamulla Bore

Corundum 55mm specimen	© Patrick Gundersen

The corundum occurrence near Inkamulla Bore is hosted in the Entia Gneiss complex. These gneisses covers an area of approximately 160 km² and are metamorphosed at intermediate temperatures (570-710°C) at peak pressures of ~ 7kbar and are postdating the regional granulite facies ordovician metamorphosis. The Entia Gneiss complex consists of supracrustal amphibolites, gneisses and calc-silicate rocks, of which kyanite is a characteristic constituent in many of the rock types. Corundum as microscopic grains has been identified both in amphibolites and a kyanite-biotite schist which contains almost 35%wt Al2O3 bulk chemistry. It is in one of these Al-rich kyanite-bearing schists, Patric Gundersen has found attractive corundum crystals:

"These Corundums were found in a VERY small outcrop of mica shist and kyanite, and to date I have only found a dozen or so specimens. They are all very well crystallized, with some intense dark blue patches (opaque sadly!) Many of the crystals feature a skeletal secondary growth of fine bladed Corundum, that forms cross-crossing lattice work across the top of the terminations and also extends beyond the edges of the crystal sides." Patrick Gundersen 2012

David Sheumack has had one of the corundum specimens analyzed by Ralph Bottrill. The XRD analysis shows that the corundum is partly altered to twinned white diaspore and some muscovite. It appears that this alteration is quite common on these corundums.

Literature:

Jo Arnold, Michael Sandiford, Simon Wetherley (1995): Metamorphic events in the eastern Arunta Inlier, Part 1, Precambrian Research 71 pp 183-205


Corundum
Australia
Northern Territory, Harts Ranges (Hartz Ranges), Mount Brady, Minstral Mine (Ruby Mine)

Corundum 2,5cm crystal	© 2009 M Goodwin

The ruby has been found in rocks belonging to the The Harts Range Meta-Igneous Complex. This complex consists of amphibolites interlayered with anorthositic gneisses and ultramafic rocks metamorphosed to granulite facies (
~800C and 10 kbar).

The ruby deposits resulted from local metasomatic alteration of anorthosite folded into ultramafic boudins as the silica poor ultramafic rocks drained Si from the anorthosite, leaving the anorthosite with high Al/Si ratios. It is believed that ruby could only be formed in highly altered anorthosite that was already enriched in Al relative to Si.

The deposit was discovered in the late 70-ties, and crystals up 5 to 12 cm. in size and of weight up to 5 kg was found.

Literature:

A,C. Storkey, J Hermann, M.Hand and I.S Buick (2005); Using In Situ Trace-Element Determinations to Monitor Partial-Melting Processes in
Metabasites, Journal of Petrology Vol 46, No 6 pp 1283-1308

R. W. Lawrencea, P. R. Jamesa & R. L. Oliver (2007): Relative timing of folding and metamorphism in the ruby mine area of the Harts Range, central Australia- abstract, Australian Journal of Earth Sciences, Volume 34, Issue 3

V. Bukanov (2011): Corundum, Russian Mineralogical Society website


Corundum
Australia
Queensland, Mount Isa - Cloncurry area




Corundum
Australia
Queensland, Mount Isa - Cloncurry area, Mount Isa district, May Downs Station, Corundum Crystal locality




Corundum
Australia
South Australia, Flinders Ranges, North Flinders Ranges, Arkaroola Region (Arkaroola Station), Mt Painter area, Corundum Mine




Corundum
Australia
Tasmania, Blue Tier district, Weld River

Corundum 16mm crystal	© Andrew Tuma

Corundum ca. 6mm crystal	© R Bottrill 2012

Corundum
Australia
Tasmania, Boat Harbour, Sister's Creek

Corundum 0,87 cm crystal	© Jasun McAvoy

Corundum
Australia
Victoria, Amphitheatre,Sedimentary Holdings alluvial gold operations




Corundum
Australia
Victoria, Carapooee, Alluvial gold mine

Corundum FOV 12mm	© Judy Rowe

Corundum
Australia
Victoria, Cardinia Shire, Gembrook




Corundum
Australia
Western Australia, Gascoyne Region

Corundum 5,8 cm specimen	© R Bottrill

Corundum is known from many places in the Gascoyne Region, which is a rather remote area even by Australian standards. It appears that the majority of corundum occurs in eluvial or alluvial deposits, where the corundum crystals have eroded free from their host rocks. White crystals have been reported from both Eudamullah Station and Yinnietharra station in the neighboring Pilbara region, whereas blue crystals are reported from the Mt Sandiman area. The crystals occur primarily as tapering bipyramids, either as stand alone crystals or as groups. The crystals can be minimum 6-7 cm long.

There has been some interest in the geology of this area over the last decades. The interest is primarily sparked by a potential for economic development of metals (gold) and REE sands ( monazite). The understanding of the geology of the Gascoyne complex is getting better, but the sequence of the geological events is not yet fully agreed upon. The literature list gives an overview of the geology in the area. None of the reports that I have been able to find describes any corundum bearing rocks, but several rock types belonging to the now redefined Morrissey methamorphic suite contains Al-rich metapelites metamorphosed to amphibolite facies and similar rocks may be the host rock for the corundum crystals.

Literature

Tom Kapitany, Ralph Bottrill (2012): Corundum Australia, Mindat messageboard

Lesley Wyborn and Carole Hensley (2001): Gascoyne Province synthesis, Geoscience Australia.

S. Sheppard, S.A Occhipinti, D.R. Nelson (2005): Intracontinental reworking in the Capricorn Orogen, Western Australia: the 1680 – 1620 Ma Mangaroon Orogeny, Australian Journal of Earth Sciences vol 52, pp443 – 460

D. McB. Martin, S. Sheppard, A. M. Thorne, T. R. Farrell, and P. B. Groenewald (2007): Proterozoic geology of the western Capricorn Orogeny — a fi eld guide: Western Australia Geological Survey, Record 2006/18, 43p.

S.A. Occhipinti, S. Sheppard, C. Passchier, I.M. Tyler, D.R. Nelson(2004): Palaeoproterozoic crustal accretion and collision in the southern
Capricorn Orogen: the Glenburgh Orogeny, Precambrian Research 128, pp 237–255



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Edited 7 time(s). Last edit at 09/17/2012 09:59AM by Olav Revheim.

Olav,
Corundum is too small to break it up for each country. Now you need to add to it and do corundum for all the rest of the world.

Rock Currier
Crystals not pistols.

Rock,

I know, I try to break up corundum by continent, Australia being the smallest. I am working now to add pictures to the Europe and Africa ones.

Olav

Olav,
If needed, here is another Australian corundum for your files fro,m a relatively unknown spot in NT, Australia, Inkamulla Bore in the Harts Range.

Corundum crystal 1mm X 14mm

Olav,
OK, lets see how big the article gets, perhaps it won't fit in one article. The reason I like to put all the pictures of a species in one article is that when people are looking at images of a particular mineral when they have one but don't know where it is from, it is easier for them to look through an article that includes all localities rather than have to click around on different articles to try and find what they want.
Rock

Rock Currier
Crystals not pistols.

David,

That is a nice sapphire, is this Inkamulla mine the locality, or somewhere nearby?

Do you have any further information on this locality?, such as how common corundum is, how it occurs, how large the best crystals get and also other information if you have.

Thanks

Olav

Hello Olav,
The specimen in question was collected from a discrete deposit in the Inkamulla Bore region, not Inkamulla Mine. A rather interesting and eye catching specimen. I realise/understand from Mindat's management, Ralph B. that this is the first time corundum has been reported at this site/area. I have spoken to the collector of this specimen and further information/post should follow.

Great work and further good luck with your informative article

David

Rock,

I did try to include all corundum into one article. I maxed out after only a handful of the most profilic localities, and even before I started to look into Burma and Sri Lanka. I agree that it is a lot easier to have one article, or split on varieties rather than geography if one species will need more than oine article. I thought long and hard about splitting the article into one for ruby and one for sapphire, but left this idea because I didn't want the pink sapphire vs. ruby discussion. Also, both red and blue corundum are found at many localities. I've landed, so far, on a continent split, but this can of course be changed when we have all the text blocks in place.

Olav

thank you David

Following up on David Sheumack's previous post, here's are some more details and images of the new Corundum find that I made a couple of years ago in Hart's Range, central Australia. The closest accurate locality for this deposit is Inkamulla Bore, which is a well known landmark in this region of the Harts Range. The only locality with a similar title that Mindat has listed is "Inkamulla Mine" which I have not heard of before. It could be this has been mislabeled. I'll try to find some confirmation of the location of Inkamulla Mine before adding a new locality for the bore, to avoid cluttering up the database.

These Corundums were found in a VERY small outcrop of mica shist and kyanite, and to date I have only found a dozen or so specimens. They are all very well crystallized, with some intense dark blue patches (opaque sadly!) Many of the crystals feature a skeletal secondary growth of fine bladed Corundum, that forms cross-crossing lattice work across the top of the terminations (in the closeup photo below) and also extends beyond the edges of the crystal sides. This can be observed in the photo below, on the left side of main front face of the specimen.

Patrick,

I assume that yours and Davids corundums come from the same locality as these?. I'll add to the desciption later.

Thanks

Olav

Olav et all, this is looking very good , excepting a few wonk picture links. There is an obvious need for more Queensland specimens, maybe from Gayle and Lin Sutherland eg Se recent Aust Gemmologist.
I can add some information on some sites if you like.

Regards,
Ralph

Ralph,

Any help will be highly appreciated.

Olav

Hi Olav,

Yes, all of those blue Corundums are from the same location (collected by myself) in the Inkamulla Bore region. The Ruby specimens further down on your link come from a separate location further west.

Thanks!

Patrick

Patrick,

Thank tou for the information you have provided. I have entered a draft text on the Hart's range corundum occurrences. From your perspective, do the texts seem OK?

Thanks

Olav

Hi Olav,

Thanks for adding and compiling the info, yes the text sounds fine to me.

Thank you!

Patrick

Hello Olav,
Some interesting information concerning the Inkamulla corundum. Since obtaining this specimen from Patrick, he and I have playfully debated the identity of the associated whitish crystals. The last entry in your article was: "Many of the crystals feature a skeletal secondary growth of fine bladed Corundum, that forms cross-crossing lattice work across the top of the terminations and also extends beyond the edges of the crystal sides."

To solve this corundum conundrum I decided to submit a sample for XRD analysis at Minerals Resources Tasmania. The results were obtained from Ralph Bottrill yesterday and are as follows: corundum var. sapphire, partly altered to twinned white diaspore and some muscovite.
XRD confirms corundum, diaspore and muscovite (R Bottrill).

The original description (http://www.mindat.org/photo-484010.html) has been ammended and I have also added and additional close up picture of the diaspore crystal association with the corundum (http://www.mindat.org/photo-487011.html) for your perusal.

Best wishes,
David

The blue corundum from Yinnitherra is actually from Mt Sandiman Gascoyn mineral field
The white corundum is from White well Yinnitherra

David,

Thank you very much for your contribution to this article. Please let me know if I have used the information you have provided in a good manner.

Tom,

Thank you for your locality information. As I am not at all familiar with this area, I hope that you can clarify some more around the origin of these corundums. I have found several references to white corundum crystals resembling the one pictured here from Eudamullah Station in the Gascoyne region, whereas Yinnietharra is in the Pilbara region. Are these localities related in any way ( geography, geology or other)? The listed locality in Mindat for this white corundum (Wodgina) is referenced from an article in the American Mineralogist from 1928, but this article describes violet corundum in nice crystals from Abydos. Obviously Mindat are less accurate in this area then other, more populated areas.

I would also appreciate if you could describe the Mt Sandiman loclity a bit closer, as this locality is not described in Mindat, and I have not found any other reference on these occurance, and your assistance will enable more accurate locality descriptions.

Thanks and regards

Olav

The blue corundum from WA came to me labelled Yinnietharra, but it probably originated with Tom, so I shall accept that and change it.

From the little i know of the area, Eudamullah, Yinnietharra and Mt Sandiman all lie, about 100km apart, (very close for this area) in the Gascoyne Region, just to the south of the Pilbara Region. Geologically they are all in the Gascoyne complex, a metamorphic belt between the Pilbara and Yilgarn. The Wodgina area is about 500km north, in the Pilbara, I am a little doubtful about corundum there, but don't know the area, so hopefully Tom knows more. Unfortunately many of the W.A. Sites are very poorly categorized regarding regions etc.

Regards,
Ralph



Edited 2 time(s). Last edit at 09/15/2012 11:03PM by Ralph Bottrill.