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Need help with locality on corundum

Posted by Donald Slater  
avatar Need help with locality on corundum
August 04, 2012 08:52PM
I just acquired this large corunudum crystal in and old collection. I looked through the data base and found nothing like it. I know it is sometimes hard to determine a location but this one is pretty unique in size and color. It is a deep forest green, 6cm long, 4.5-4.8 cm across the top and weighs 355 grams. Does anybody have any ideas. Any suggestions would be greatly appreciated.


Edited 1 time(s). Last edit at 08/04/2012 10:00PM by Donald Slater.
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Re: Need help with locality on corundum
August 04, 2012 11:02PM
In "National Audubon Society Field Guide to North American Rocks and Minerals" is a photo of a grey-green 'Corundum in Gneiss'.
Among other corundum occurrences is mentioned "Crystals as much as 35 cm (14") in length have been observed in gneiss near Salesville, Gallatin Co., Montana..."

I hope it helps.

avatar Re: Need help with locality on corundum
August 06, 2012 03:02AM
It could be from many places, but you might get lucky and someone here might give you a definite locality because of their experience with the locality.

Rock Currier
Crystals not pistols.
Re: Need help with locality on corundum
August 06, 2012 08:43AM
I've collected all of the in situ Montana corundum locations.

There are only two colors of corundum in those places.

Gray, sometimes with a hint of blue, and plum color.

Never green.

There are many placer occurrences such as Cottonwood Creek, and those display every color of the rainbow, but those "sapphires" are never as large as what you describe.

Re: Need help with locality on corundum
August 06, 2012 10:27PM
are you sure it's not a green apatite at this
avatar Re: Need help with locality on corundum
August 07, 2012 01:23AM
Quite a lot of this 'Forest Green' Beryl turns up on e-Bay, usually crudely carved and described as 'Emerald'.. The usual source for the ones I see is given as India.
avatar Re: Need help with locality on corundum
August 07, 2012 10:05PM
Thanks for the information all. I knew that it would not be easy to determine location but I do get lucky once in while. I hoped the size and color may be distinctive enough that someone might have seen one like it or may even have one in their collection.
Re: Need help with locality on corundum
August 07, 2012 11:49PM
It looks similar in luster and habit to ones I have from Madagascar. Mine are pale blue and lavender, but I have seen green ones in the same lot.
avatar Re: Need help with locality on corundum
August 14, 2012 10:22PM
Thanks Ken. It could be a possibility. I think it is fairly old. I don't think the man has collected anything is a long time. It seems to be a lot harder to determine the locality than I thought. I am still counting on luck. I like it even without the location but it would be nice to know.

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