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[Elise]

I have a question regarding how mineral collectors and mineralogists try to establish origin if it is not known; specifically whether inclusions are part of that process and if so, one which is found in Burmese corundum - a liquid inclusion in the form of a healed fracture with a folded appearance - or does the exterior of the corundum crystal usually obscure the interior?

Pictures can be seen in various texts such as PhotoAtlas Vol 1, Journal of Gemmology 1994, vol 1, Dr. Gübelin's Internal World of Gemstones and Ted Themelis' Gems & Mines of Mogok, the last as an inclusion in ruby, which was the first I have seen referenced in red corundum (can I call it ruby in this crowd?); all others mention only blue sapphire (Gübelin, Koivula, Hughes) and seem to imply these folded healed fractures only occur in Burmese blue sapphire - though JK's latest PhotoAtlas Vol 3 and Dr. Roedder's comments on the validity of inclusions as indicators of specific origin allow that ambiguity remains, especially as new occurrences become known.

My question is whether they have been seen by mineralogists in corundum from other localities of similar or differing geology and is there any idea of how they form? My thought was that it arose originally from a chonchoidal fracture, but I don't know why that couldn't occur elsewhere. Part of the reason I am asking is because I observed one of these in a color-change sapphire - picture below, where you can see a bit of the rounded, folded nature in the middle of the length of the healed fracture - sometimes they can be quite dramatic as the images in the above references illustrate better.

I am co-authoring a book which will include this stone and would like to add what information I can about this structure - why where and how are the classic questions already put to me by the public and by mineralogists and though I have plenty of references to the geology and to the inclusion, I haven't found any alternative information for other possible localities or ideas about the folded appearance.

Though this is from the standpoint of "forensic gemology," my audiance is an academic one and in a geology department, so I am hoping this is a welcome question on this forum.

Best wishes,
Elise

[Jason]

The closest corundum(ruby) that is not of burmese origin but is similar are Tajikistan rubies..they form in the same type marble deposit and tajik's are passed off as burmese rubies every so often but GIA origin reports can pick them out..most of the older books don't have info on tajik rubies as they were not discovered until not to long ago and on-site samples are/were hard to come by. Maybe try and track down Richard Hughes or Vincent Pardieu as they are pretty much the foremost authorties on gem grade corundum and there locales including the more recent mozambique finds.

[John S. White]

By "corundum origin" are you referring to paragenesis or to locality? My gut feeling is that any ruby (perfectly valid term in this context) that formed in marble can show the same types of inclusions, but I have not studied rubies from different source areas.

[Elise]

[Jason]

Sorry i meant to say the tajik resemble Afghan(jagledek) and Vietnam rubies and were being passed off as burmese rubies..oops..healed fractures can happen in many stones depending on how many stages of growth it has..scott just did a little report on rehealed quartz . When it comes to inclusions and microscopic sizes then Gemmologist are more atuned to that subject..not saying any mineral folks on here don't/wouldn't know but a gemmo's job is to take the darkfield scope and study the inclusions.. a la origin reports like you can get at AIGS or GIA..if Jordi doesn't mind I would like to send you here also..it's the "stone and inclusions" section..throw up that picture of yours and i am sure one of the ruby experts over there can help also
https://www.gemologyonline.com/Forum/phpBB2/viewforum.php?f=21
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[Elise]

Thank you, I am familiar with gemological technique and have some excellent resources to draw on, but I was hoping for some new insights from the perspective of the world of unadulterated minerals, either gained from observing specimens of known origin and geologic environment or gained in the course of trying to determine where specimens might come from given their characteristics (and again, I don't know whether studying inclusions is part of that process for collectors). A gemologist has even less to go by when examining a cut stone and is effectively working backwards from observations. Of course there are several well-known people of various disciplines who work in the field of gemology who observe rough material at the source or from unambiguous sources, but this still remains a limited sampling and any origin determination of an unknown coming into a lab is stated as an opinion, if noted at all - I would assume this would hold true when looking at an unknown mineral specimen. I would also assume that intact mineral specimens generally contain more inclusion suites than the relative desert within a stone cut from gem quality specimens; perhaps this would mean that collectors might have some valuable experience in this area. My own mineral specimens lend themselves quite nicely to inclusion study, but they were acquired for that purpose.

But, back to the morphology of the healed fracture, isn't it odd - for lack of a better word? I have been working alongside a gifted mineralogist for more than a year now who has taken my own inclusion work to new levels with his input, but this one leaves so many questions which remain unanswered. I am not trying in any way to assign origin to this particular cut stone; only explore why this form occurs and only in this limited locality supposedly (I hold out for other localities and maybe other mineral species). In digging deeper into Dr. Roedder's writing last night, what I took away was that metamorphic processes play hell with inclusions; maybe that's all too true.

Best wishes,
Elise

[John S. White]

Elise:

I suspect that inclusions such as you are alluding to are very difficult to observe in raw crystals, and I would be very surprised to learn that anyone has actually noted them in a gem quality ruby crystal. However, you might get lucky and reach a visitor to this Forum who has such an inclusion in an uncut crystal from some locality other than Myanmar. Hope it happens.

[Jason]

Did you try hughes?

https://www.ruby-sapphire.com/r-s-bk-ch5.htm
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