sapphire with inclusions of mic

Gem Related Discussion
1

Hello Miss, Sir
I would like to contact you to request information regarding a sapphire that I own.
It is an opaque sapphire that I bought in a flea market in Paris with a weight of 6900 grams, after having it appraised at the national scientific research center he knows that it is a sapphire with inclusions of mica, the stone was cut in Germany in Idar Oberstein, the current weight is 4000 grams, unfortunately there was no star appearing but we can clearly see the needles or the streiss on the whole of the rock.
After asking professionals for advice and after doing research on the internet, I was unable to obtain information on this subject (sapphire with mica inclusions).
For this I come to ask you so that you can inform me about this type of inclusion, is it a rare stone, does it have value, or as they say it is used to make ashtrays?

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I thank you in advance for your attention to my request and I remain at your disposal for any additional information you may need.
Sincerely

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2

Welcome to the forum!

It is very difficult to make a positive identification using images, alone. However, this stone appears to be a very large piece of sodalite.

Here are several resource pages for you to review:

Cheers!

Troy

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Thenk you for your answer, you are not the ferst to say that is sodalite but the stone has been appraised twice, it is indeed sapphire

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The certification report does not match the stone you presented.

Dimensions are wrong calling out a stone that is less than10mm, where the stone you presented is larger than your hand.

The certification also reports a stone that only weighs 0.34g. When you stated the stone weighed 4000g after being cut. The QR code… links to a stone report for a rough sapphire that weighs 0.34g.

Cheers!

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what’s the point of making a lying publication. the French gemmology laboratory does not have the expertise capabilities for large specimens, I was obliged to cut a sample to have it examined too, also on the expertise certification it does not mention the inclusions, so I filed a another sample at the national scientific research center, which was tested by a digital scanning microscope, I am attaching the report. also in the photos we see mica needles, have you ever seen sodalite with mica inclusions? This stone cost me a lot of time and money until then, the only laboratory that can give me expert assessments of the stone is the Gübelin laboratory in Switzerland for €4000 plus transport costs. My question was simple at the beginning, is it worth spending so much money on this stone? Kind regards

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The sample was given to us enclosed in resin, cut into two sections and polished. The surface was cleaned with ethanol and N2 (5 bars). Carbon deposition by evaporation with high purity braid (thickness 30 nm) was carried out to ensure secondary vacuum conduction in scanning electron microscopy. BSE Imaging: High resolution mosaics (25 Mpixels) were produced using backscattered electron imaging (atomic weight contrast) covering both sections, in secondary vacuum (~2 10-5 Pa) (column conditions: 15 kev, spot 4, aperture 30 µm, working distance 10 mm). Textural analysis confirms a heterogeneous, polyphase sample, presenting filled fracturing networks and small automorphic minerals included, on both sections (see mosaics 1 and 2). EDS elementary mapping: Qualitative elementary mapping was carried out on one of the sections (see mapping), in secondary vacuum (column conditions: 15 keV, spot 5.5, aperture 50 µm, working distance 11.8 mm, EDS time constant: 600 kcps/s ), with a resolution of 1500 pixels. It confirms the aluminum oxide nature of the main phase, as well as 3 distinct fillings in a large fracture: two first phases whose texture and composition seem to indicate a phyllosilicate (phase A rich in Ca and Na, phase B rich in K), and a filling phase of alumina oxide, depleted in Al compared to the main phase. EDS elementary analyses: Quantitative point analyzes were carried out in 2 zones of the first section, and one zone of the second section, in secondary vacuum (column conditions: 15 keV, spot 5, aperture 30 µm, working distance 11.8 mm, EDS time constant : 130 kcps/s). The size of the interaction pear is estimated at 1.6*2.9 µm (LP) under these conditions on this matrix. Elements with an atomic weight lower than Na are indicative (they cannot be quantified in EDS, in particular in the present case, O). Quantifications are carried out after Rho/Phi/Z correction with certified and calibrated standards (MAC CAS) under these analysis conditions. Main phase: The analyzes confirm the presence of a corundum with stoichiometry Al203, presenting in places traces of Ti, Ca, K and Mg. (Image 1 spectra 1 and 5; Image 2 spectra 1 and 2; Image 3 spectrum 6), compatible with a sapphire. Inclusions: Very rare automorphic zircons were detected as inclusions in the main phase (Image 3 spectra 1) Filling of the fracturing: A filling in 3 phases of the very numerous joints/fractures seems likely: A = Growth of an automorphic calci-sodium phyllosilicate (micas) containing traces of Mg (Image 1 spectra 3). B= Lining by a second potassium phyllosilicate phase (traces of Fe, or even Ba). (Image 1 spectra 2 and image 3 spectra 2,3,4) completely filling some fractures and partially others (see mosaic 2). C=Total filling of the residual porosity with a xenomorphic alumina oxide which does not respect the stoichiometry of corundum ("AlO2) (Image 1 spectra 4; image 2 spectrum 3; image3 spectrum 5).

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Kadda,

As I stated in my initial response, it is nearly improbable to make any gemstone identification from an image alone. The pictures you initially presented are of a very large stone. (Which is a very nice specimen, by the way).

So let us dissect this conundrum from the corundum.

I understand that your initial question was to determine whether or not additional money should be spent or as suggested, use it for carving ashtrays. If it is corundum, carving ashtrays would be an arduous task, due to the typical Mohs hardness of 9.

Therefore, based on visual features of the stone you presented:

  1. Large patches of blue to violet areas with ultra-fine crystalline granularity.
  2. Large fractured inclusions of white.
  3. No visual presence of pyrite within the matrix as a whole.
  4. Vitreous and Greasy luster. (although this may not very reliable because the specimen has been worked.)

I offered an assessment from the images which is consistent with the classic coloration and large inclusions of white calcite, interspersed with some quartzite, commonly found in Sodalite. The lack of pyrite can typically discount the specimen as being Lapis Lazuli, if presented in a rough matrix, such as seen in the images.

The two links I provided, present information that using basic rockhounding techniques, one can perform simple tests to help define or discount the classification. If your stone is corundum, it will not be scratched by a steel nail or by Glass / Quartz. Sodalite is much softer with a Mohs of 5 - 6. There are other characteristics that could be assessed as well. Including: specific gravity, refractive index, and Fluorescence.

However, the LFG gemological report becomes an enigma. Based on your statements, this is directly connected to the stone you presented initially. But you have not presented an image of the stone that is contained in the report.

So, in my defense; there is no evidence that connects the two reports to the stone initially presented to this forum.

Respectfully, I am in no way saying you are wrong, or that the lab reports are wrong. The evidence is just not consistent.

Do you have images of the stone contained in the LFG report? Not the image in the report, but images of the sample before the LFG analysis. Secondly, the SEM report (according to the dialog you posted) uses a sample encased in resin to stabilize a thin film strata coupon, typically used in a SEM analysis. This sample should have been extracted from the sample provided for the LFG report. Are there images of that?

This would be the evidence necessary to provide continuity.

Without that data, we are back to square one; my visual analysis.

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Hello Kadda, the first set of pics did look like sodalite but the second batch of pics were spot on!
I did find some info for you. There’s an eBay seller in Pakistan selling a few large specimens from Afghanistan. Maybe he can give you some info or at least lead you in the right direction?

Please tell us how it works out for you.
Ty for sharing!

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thank you JC Bell for your response and the help you give me.
Did you notice that the visual characteristics of the stone are not usual for a sapphire?
if I am on this forum it is because I trust the IGI and these professions to find answers to my questions

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You’re welcome Kadda
Yes, I did notice and I found your post very interesting. I learned something new today which is always a good thing

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Kadda,

Thank you! Greatly appreciate the additional images and test report data. The samples suspended in the cylindrical resin align with the images captured using the EDS SEM.

EDS SEM is a good at identifying compounds and elements above an atomic number 11, including compounds like Alumina, Silicates, and other oxides. Based on several statements from the report content you posted, Alumina is present in the main phase with several inclusions that match the atomic ratio for corundum.

This unfortunately presents evidence that the sample as a whole cannot be classified as corundum. The majority of material has to be corundum in order to be called it. That is simply not the case here.

Selling this material as sapphire, would be unethical, based on the EDS SEM data alone.

The LFG report and the stone you provided an image of, is a bit more enigmatic .

Comparing the stone with the one in the report.

LFG_Combine

Again, I state, it is difficult to do any assessment with images alone. The illumination and orientation of the stone would help in linking the report with the sample. They favor each other in shape, more or less.

Since the LFG report does not identify the source of the sample, it will be difficult to associate the 4kg stone with the one imaged in the report. Technically, LFG will only honor the stone imaged in the report.

I am not trying to be difficult here, so please forgive my bluntness.

As a jeweler, I am committed to sourcing quality stones for my clients. Currently, I cannot in good conscience, provide endorsement for this material being called Sapphire. Too many unknowns.

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Hi Troy, I think after Kadda found the vein was indeed sapphire, he was just inquiring whether he should invest any more time/money or if the whole piece was only ‘good enough to be an ashtray’.
The guy on ebay sells these sapphire bearing pegmatites to collectors and since they’re rare, he could probably give Kadda more info and guidance than we can…
That’s how I interpreted his post. Kadda can correct me if I’m wrong

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I find your analysis interesting,
from what you are saying, we are on two assumptions,
1 - the stone is not a sapphire and does not belong to the corundum family despite it being confirmed twice by the LFG and the CNRS and both being wrong,
the question that arises, what name is given to this type of stone, is to which family should it belong?
2- the stone is a sapphire but with a composition different from the sapphire we know.
in both cases we are on a unique stone with its composition.
my conclusion that this stone deserves its place with the rare sapphires known as the millenium sapphire, the sapphire of ophir collection, The Priceless Sapphire.

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You are quite right

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I guess I am not describing the concern sufficiently.

  1. You have a ~4 kg stone, through the effort of testing, has a potential to contain corundum. And as Jacqueline (@JCBellGG) stated in reference to the seller on eBay, the stone is potentially a sapphire bearing matrix. It is not a ‘sapphire’ as a whole. This is where the definition needs to be considered.

  2. I am not contesting the reports from LFG or CNRS. I believe the reports are independently valid. But as I attempted to articulate (rather poorly it seems), these reports are tied only to the respective samples provided. There is no connection or language in either report (unless you have not presented that here) that witnesses the samples were donated from your host stone. LFG and CNRS will endorse only what they have stated in their respective reports.

Unfortunately, the two reports do not agree with each other.

There is not enough evidence connecting your host stone to both reports. One sample has been certified to be sapphire (LFG) and the other sample, using EDS SEM (CNRS), has identified the slight existence of corundum bearing material in a large non-corundum matrix.

Without that connection, these reports are defining two separate and unique stones.

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Hello Kadda,

Thank you for the update. I am now quite intrigued by the inclusion of X-ray CT. I have employed XCT in several projects over the years to answer tough questions. With 320kV, there should be good definition between the primary matrix and inclusion boundaries, if sufficient chemical differences exist.

I hope you have a Geologist and/or Mineralogist available to examine the data collected from those scans. Their assessment / evaluation will be of great value.

Cheers!

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To be given certification upon any item large or small generally will cost more for larger and minimum cost for smaller.
Consider carving into something you desire.
Not usable as sapphire gem simply way too large for gem.
When bigger is not better try to find way to use.
I have seen carved tea cups in such material. I have seen tea pots carved out of similar rocks several carved out of jade.
Sapphire will be difficult to carve.
Depends on owners desires.
Typically large stones unless verification by certification process occurs will not reveal value sufficient to offset costs incurred. I have yet to find sales on large material items.
Most often others want smaller gems not big ones.
Due my disability I need large stones to work with as my hands shake horribly and I make mistakes in my cutting. Just a result of my pain spasms which resonate in my limbs.
I love to create carved stone necklace, bracelet, earrings, ring make a matched set of materials and maybe others will desire them. They also might make excellent gift ideas later.

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Just to add my one cent…or two cents: I think the arguments boils down to having a multimineralic rock versus a corundum mass that is filled with other minerals… either way it’s a rock, and not a monomineralic crystal. Knowing the provenance would be extremely helpful as it would put the geologic circumstances of the rock’s formation into perspective. That being absent, the presence of mica, particularly if muscovite most likely indicates that it was formed hydrothermally as part of a pegmatite mass… pegmatites that form below 2km depth are too deep to have freely circulating voids full of mineralized hot water to form perfect crystals… the lithostatic pressure compresses the rocks and doesn’t allow for free pockets to form… the result is an intergrowth of muliple pegmatitic minerals that are not gem quality. One of the best examples are the pegmatites of the Black Hills in South Dakota. Even though some of them are zoned, with a rose quartz core, nothing there is of gem quality…all of the crystals are densely intergrown…there were no free pockets or voids to grow large clear crystals. You have a rock with patches of corundum intergrown with other pegmatite minerals. Studying the non corundum minerals would give you a better chance at determining how your specimen formed. If they contain lithium or beryllium, that would cinch it as a pegmatite, but not necessarily be present, as the host rock would have to be ultramafic to syenitic…deficient in silica towards undersaturation… Li and Be would be contained in tourmaline only… It’s highly doubtful that this is a metamorphic corundum embedded in marble. I could be wrong on that, but it’s definitely not of gem quality… cutting it into slices won’t find you an area of gem quality corundum only because of the way it formed. Size alone doesn’t count as much. The material is suitable for carving or left alone as a rock specimen. Doing more high tech analysis such as electron microprobe or mass spect will cost a bundle and would cost more than the value of the rock itself…unless you can get it done for free or at minimal cost as a geologist at a university that does petrology work… the last quote I got for whole rock analysis was 2K per sample…that was before inflation took off…the photo of the crystal sample submitted by JCBellGG shows clearly the hexagonal crystal structure of corundum. It too is an intergrowth of mica and likely other minerals…it has value as a mineral specimen but not as a crystal that can be cut into high quality gems.
That being said however, corundum in pegmatites are quite rare…there are only a few locales where syenitic peraluminous pegmatites occur, allowing for the formation of corundum… If your specimen is a pegmatitic corundum, it could have come from Alvand batholith in western Iran, the southern Urals, or from metamorphosed ultramafic rock in Pakistan or Afghanistan. Conditions for forming pegmatite hosted corundum has to be peraluminous, silica deficient and alkalic…not the usual type of pegmatite. Your specimen could be a rare one geologically.

I hope there’s a professional geologist/petrologist out there… comments would be welcome… I am only an amateur, could be entirely wrong.

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thank you!

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