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LocalitiesKokcha Valley, Badakhshan, Afghanistan
16th Jun 2017 03:19 UTCIan Nicastro
-Would it be useful to add this as a reference for the Dravite from Koksha Valley?
-Would it be worth it on the Hazrat Saeed page to mention that the Dravite and Dravite-Uvite attributed to Koksha Valley are likely from Hazrat Saeed specifically, since multiple specimens attributed to Koksha Valley have turned up with both sapphire and blue dravite in the same mica matrix? And Hazrat Saeed appears to be the only Sapphire source in Koksha Valley.
-Only a totally different note... multiple sapphire crystals of specimen quality from Hazrat Saeed I have examined have a weakly radioactive mineral on/in them. Peter Slootweg and I hypothesized that it could be Zircon or a Microlite Group mineral. The mineral giving the radiation has a corroded looking shape and a grey color and is likely mistaken for books of mica at a quick glance. Not every sapphire has it, but quite a few do. This is the first time I have ever seen sapphire specimens with detectable radioactive inclusions. I haven't had a chance to have these analyzed.
16th Jun 2017 03:31 UTCAndrew Debnam ๐
Andrew
16th Jun 2017 11:25 UTCReiner Mielke Expert
16th Jun 2017 23:41 UTCRob Woodside ๐ Manager
The Dravite from the Kokcha Valley is yellow green and from a white schist occurrence https://www.mindat.org/loc-253959.html. There may be more than one such occurrence, but there were no blue dravites here.
I'll add this to Hazrat Saeed https://www.mindat.org/loc-255436.html Please check it.
17th Jun 2017 07:18 UTCIan Nicastro
Thanks for your help, and I agree with you that those are two distinctly different dravite sources.
17th Jun 2017 14:09 UTCAndrew Debnam ๐
Thanks
Andrew
17th Jun 2017 16:19 UTCIan Nicastro
17th Jun 2017 17:52 UTCRob Woodside ๐ Manager
This piece has the Sar-e-Sang River assemblage. https://www.mindat.org/photo-598289.html Click for other views
This piece is darker and thinner https://www.mindat.org/photo-329797.html
This looks like a pseudo after the last habit https://www.mindat.org/photo-566823.html
17th Jun 2017 18:08 UTCAndrew Debnam ๐
Andrew
17th Jun 2017 20:50 UTCUwe Kolitsch Manager
Basaltic sapphires from Vietnam contain, among other minerals, pyrochlore and baddeleyite.
Corundums/rubies from both basalts and marble may contain zircons.
Van Long, P., Quang Vinh, H., Garnier, V., Giuliani, G., Ohnenstetter, D., Lhomme, T., Schwarz, D., Fallick, A.E., Dubessy, J. and Trong Trinh, P. (2004): Gem corundum deposits in Vietnam. Journal of Gemmology, 29, 129-142.
18th Jun 2017 01:18 UTCJosé Zendrera ๐ Manager
Also the response to UV is quite different. In Dravite samples the mica has a slighly yellowish fluorescence while that one with the sapphires is absolutely inert. And maybe the most significative difference: corundum from Hazrat Saeed is fluorescent in white o soft blue zones while that present in dravite samples is not.
I don't know if the photos have grasped the differences...
18th Jun 2017 17:08 UTCIan Nicastro
I've actually come across large sapphires on both what I refer to as the 'greenish' mica matrix and the more 'brownish' mica matrix from Koksha Valley area. I've gotten detectable radiation signals from sapphires on both types of matrix 2-3x above baseline. I agree that the Dravite definitely does seem to occur only on the green/bluish mica matrix. I imagine there are probably multiple tunnels at Hazrat Saeed and so maybe the differences in what we are seeing might be attributed to variability in chemistry across the deposit.
I've never seen pink tinged mica from there until now, but I found another photo online besides your specimen. I also have to wonder if acid cleaning could be playing a role in things, as mica from local pegs where I live will often look green after acid cleaning, but brownish gold before. Although you mention the greenish/bluish mica on the Dravite matrix giving yellow fluorescence, I do not observe that with SW UV on my Dravite specimens green matrix. I do see fluorescence in the white areas of the sapphire just like you mentioned.
Until someone treks out to the remote sapphire area I doubt we will know what's actually going on.
18th Jun 2017 18:03 UTCRob Woodside ๐ Manager
18th Jun 2017 19:48 UTCPeter Slootweg ๐
Jose is right that the sapphires in the green mica do not show any fluorescence and the big sapphires show a bright orange fluorescence at the white tips of the crystals. Many of these specimens have been oiled that may alter their reaction under UV. The only thing that bothers me, is that I have never seen the two types offered for sale at once, as from the same locality. Even in big lots of the big sapphire in brown mica material I have never encountered a green dravite bearing specimen and vice versa. Also the pink mica is something I have never seen myself. my initial thought it was staining from the pink toiletpaper these specimens are often wrapped in.
Like Rob says, until somebody goes up there and collects the facts it's one big educated guess.
19th Jun 2017 21:59 UTCJosé Zendrera ๐ Manager
To add more complexity to this matter, let me show the backside and a lateral view of my dravite sample.
Some zones of the mica have deep pink color:
Lateral view:
Under a 365nm LED
20th Jun 2017 05:20 UTCIan Nicastro
I assume that's a mineral and it's not a dye... i.e. if you put that in water, the pink doesn't leach out. I only ask because I have received Hackmanite crystals that were dyed before from the region. Fractured translucent crystals had dye placed in the fracture and then were glued back together.
20th Jun 2017 09:52 UTCJoel Dyer
Raman - if you hit the right spots - should possibly bring up organic dye compound peaks as well...or else sensible spectra related to natural pink mica...
Cheers,
Joel
20th Jun 2017 19:45 UTCRob Woodside ๐ Manager
21st Jun 2017 14:45 UTCJosé Zendrera ๐ Manager
21st Jun 2017 14:45 UTCJosé Zendrera ๐ Manager
28th Jun 2017 23:50 UTCJosé Zendrera ๐ Manager
The high Mg content do not fit with muscovite. Maybe phlogopite?
Pink mica in my dravite specimen gives also a similar spectra. After checking metals content without find significative differences between clear and fuchsia micas, it was found that fuchsia color is soluble in alcohol, which indicates a probable artificial dyed. What a bad surprise!
Comments will be welcome. Thank you.
LIBS comparative of clear and fuchsia mica.
Metals content is very similar which seems to indicate that fuchsia color do not comes from a metal.
After this comprobation the analist checked fuchsia color solubility in alcohol with positive result, which means that fuchsia color is an artificial dyed.
Metals content is very similar which seems to indicate that fuchsia color do not comes from a metal.
After this comprobation the analist checked fuchsia color solubility in alcohol with positive result, which means that fuchsia color is an artificial dyed.
29th Jun 2017 17:57 UTCJosé Zendrera ๐ Manager
1st Jul 2017 06:53 UTCIan Nicastro
27th Mar 2020 03:06 UTCFrank K. Mazdab ๐ Manager
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are ยฉ OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 25, 2024 06:59:25