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GeneralIndonesian purple chalcedony
8th Jun 2016 10:57 UTCPeter Slootweg 🌟
Peter
8th Jun 2016 11:27 UTCKeith Compton 🌟 Manager
They certainly look real to me, or at least the two that I have viewed up close.
Very nice under a scope too.
The "nodules" average around 1-4 mm in size. I would consider them too small to be artificially produced or carved like those Chinese "grapes" which are either quartz or fluorite and rounded with some form of sphere machine - basically all half spheres ground out of a solid mass. Many look very good admittedly but most have crude polishing around the base and they are obviously fake.
These from Indonesia look totally different.
Whether they are chalcedony or whether they could be called Amethyst - I am not sure but I think Chalcedony is correct
It would be good to have them analysed to ensure that they are not another mineral altogether. As more are appearing, I'm sure someone will do a definitive test. I see that some are described as Suiseki Chalcedony (those who grow Bonsai will be familiar with the term).
They are very nice.
I would certainly like to see more literature on the location.
Cheers
Keith
8th Jun 2016 13:35 UTCDavid Von Bargen Manager
8th Jun 2016 13:56 UTCAlfredo Petrov Manager
And I wonder whether chalcedony can be colored by the same mechanism that colors amethyst? And then what would we call it?
Some parts of the deposit yield green balls rather than violet ones. Haven't had a chance to look at it under high power yet, so idk whether the green is intrinsic to the silica or due to an admixed substance like celadonite.
Some sellers at the Tokyo show had it labelled as being from Sulawesi, but none had visited the deposit. Eventually an exact locality will be found out, as usual, I suppose. Patience.....
8th Jun 2016 15:07 UTCAmir C. Akhavan Expert
http://www.mindat.org/loc-125579.html
The same probably happens here, too.
I could not think of anything that would generally preclude chalcedony (length-fast or lenght-slow) from possessing amethyst color centers. Of course, too many impurities could destabilize color centers and prevent their formation.
I think I've seen similar specimens from another locality, but can't remember from where.
You can heat a small piece to 300-350deg C and see what happens to the color. If you are very patient (several months), try to bleach one in the sun or UV.
8th Jun 2016 15:46 UTCRiccardo Modanesi
What you call "chalcedony" is truly amethyst. Amir is right: in Hungary some good specimens of this quartz, crystalized this way, are found. Therefore I fully agree with Alfredo. I think the specimen represented in the photo is real and natural.
Greetings from Italy by Riccardo.
8th Jun 2016 21:48 UTCŁukasz Kruszewski Expert
9th Jun 2016 10:48 UTCPeter Slootweg 🌟
9th Jun 2016 19:16 UTCTravis Hetsler
11th Jun 2016 15:34 UTCAlfred L. Ostrander
11th Jun 2016 16:48 UTCTravis Hetsler
17th Jan 2017 01:01 UTCKEITH (Keith {Not Given})
17th Jan 2017 02:42 UTCAlfredo Petrov Manager
7th Mar 2017 14:40 UTCTim Jokela Jr
For anybody wondering, it is indeed natural, not carved, dyed, or anything.
Found as individual spheres to large clusters, floaters, no matrix, in clay.
7th Mar 2017 15:02 UTCWayne Corwin
10th Mar 2017 16:42 UTCTravis Hetsler
http://www.indoagate.com/manakarra.html
10th Mar 2017 18:41 UTCUwe Kolitsch Manager
10th Mar 2017 18:56 UTCJolyon Ralph Founder
24th Mar 2017 12:11 UTCChristopher Jolicoeur
PS I am new... nice to meet you all! -Chris
24th Mar 2017 15:00 UTCUwe Kolitsch Manager
I would choose a different mentor.
24th Mar 2017 15:10 UTCChristopher Jolicoeur
24th Mar 2017 16:35 UTCAlfredo Petrov Manager
24th Mar 2017 16:53 UTCChristopher Jolicoeur
24th Mar 2017 19:25 UTCJolyon Ralph Founder
There are many other 'trade names' that don't accurately represent the mineral species described'
'Bohemian Topaz'
'Herkimer Diamond'
'Moss Agate'
etc etc etc
It's not up to us to create a new scientifically accurate name for this material. We have one already, and it's this.
For trade names, we simply report what names are being used and what the material really is.
Jolyon
6th Apr 2017 01:17 UTCJason Evans
I got this specimen simply because I thought it looked nice, and it's turned into something far more interesting than I expected!
Are there any links to photos of quartz showing this habit?
6th Apr 2017 04:26 UTCClifford Trebilcock
I have also noted these tiny dumbbell shaped crystal forms in a batch of small groups of purple chalcedony balls.
To me the they appear to be made up of tiny quartz crystals. Also noted individual regular shaped quartz crystals
on occasion attached to some spheres. The dumbbell shaped forms remind me of many of the artichoke quartz
crystals from the Francon Quarry in Montreal.Interesting specimens under the scope.
Cliff
6th Apr 2017 17:28 UTCScott Rider
One of my specimens color range goes from a pasty white, to green to some orange, and finally purple. The white aggregates almost appear to be included by a clay like mineral. And the orange almost appears like iron-oxides... So maybe there is a lot more involved on at this location than we speculate.
The one thing I did notice is that the chalcedony specimens from some parts of Maharashtra, India are very similar. Not the color, as they are usually colorless, but the crystal forms are quite similar. I have a few pieces from there that have pretty much the exact same crystallization from India. Little spheres that appear to be made up of tiny terminated quartz crystals. Cross sections reveal that there could be at least 2 generations, a fiberous acicular formation of chalcedony making up the majority of the sphere, topped off by a 2nd gen, macroscopic "regular" quartz terminations. It is just like the Indonesian material.
Either way, I love these specimens. If you get a good one, they sparkle with a purple glow that is truly unique!!!
6th Apr 2017 20:52 UTCAlfredo Petrov Manager
7th Apr 2017 01:06 UTCDoug Daniels
7th Apr 2017 01:36 UTCPeter K. Szarka
I've watched the evolution of this stuff's availability on eBay from the start. These first started appearing commonly from Indonesian sellers on eBay well over a year ago, closer to two. Then YouTube videos started showing up with Indonesians selling the material. Chinese sellers next appeared with them next a few months later. Price went up, size came down on cherry-picked specimens. Finally, a few Americans started listing these in the Fall of 2016. Now there's a flood of this material everywhere.
And here is where I'd consider this topic eligible for inclusion in this thread as a marketing ploy. In person, the vast majority of these specimens look much the same as many other chalcedony dug out of clay. Dull, earthy, with no sparkle. But with the huge influx of grape chalcedony/grape agate occurring early summer 2016, sellers' specimens started taking on great lusters. I suspect oil, silicone, leafshine, water, etc. is being used to 'enhance' them. Not exactly a new ploy in the mineral business. And this is as far as the deception goes I think. The actual specimens are real. But you'll have to watch for 'enhancement'. A soapy water wash of a glistening piece might disappoint a buyer.
7th Apr 2017 01:52 UTCPeter Slootweg 🌟
23rd Apr 2017 17:18 UTCcascaillou
https://www.mindat.org/forum.php?read,62,369000,369000
25th Apr 2017 04:24 UTCMarek Chorazewicz
Best Regards,
MarekC
25th Apr 2017 11:11 UTCJoel Dyer
Have you got any of the spherules analyse? XRD might be able to tell you the crystallization degree of the material.
Raman spectroscopy will tell you even better what SiO2 phase this is, partiularly if it contains for example moganite.
I'm in the process myself of starting - or actually continuing - a joint publication project with an experienced mineralogist, concerning moganite & quartz content in Finnish vs foreign chalcedony & some other similar SiO2 materials.
Of course, there have been similar studies carried out already, but no such comparitive work in Finland yet, as far as I'm aware and have been told. Please correct me if this is not true.
So, if you would like me to include some of your material in the study, I'd do it for nothing, but would need a few "balls" of the stuff, preferably slightly different looking / different shades. The same goes for other chalcedony/flint/agate etc chip donations. You will be provided with the anaysis results, no charge. This is a one-off project deal for me, for a limited time only ;-) .
You (whoever it is) can get hold of me via a private message or preferably via firstnamelastname"at"hotmail.com
Cheers,
Joel
26th Apr 2017 00:13 UTCPeter K. Szarka
Thanks for that link. I was not aware of it and it's highly informative. The scope of treatments is truly astonishing.
20th Jul 2017 10:52 UTCMacro Cosmos
https://flic.kr/p/VFeC8v
Tiny cubical formations essentially form the botryoidal structure, really interesting. They are truly amazing!
17th Aug 2017 14:58 UTCTim Jokela Jr
The sparkly material is sparkly because of countless minute quartz crystal terminations.
Interestingly, one piece can have both sparkly and smooth spheres, as well as green and purple.
Fantastic stuff under the scope, photomicrographers need to get busy!
17th Aug 2017 15:18 UTCTim Jokela Jr
The spheres are fibrous in cross section, but surfaces can be composed of crystal terminations, and both sharp single micro crystals and clusters can be scattered upon the spheres, or even make up a matrix for the spheres.
Specimens can be composed of both sparkling exterior crystalline, or smooth, non-crystalline spheres, side by side.
Is it truly cryptocrystalline chalcedony, or crystalline amethyst???
Upon what specific evidence was the term chalcedony chosen by MinDat?
17th Aug 2017 18:17 UTCAlfredo Petrov Manager
18th Aug 2017 02:31 UTCDoug Daniels
18th Aug 2017 11:27 UTCReiner Mielke Expert
27th Sep 2017 19:15 UTCaco farid
10th Oct 2017 07:40 UTCJoel Dyer
I received just recently from Tim Jokela 3 different looking samples: darker purplish, lighter purplish and green. All of the samples show clear crystallinity, with varying sharpness of light refraction.
The lighter purplish material showed clear signs of moganite (10-15%), the other samples just quartz peaks, compared to reference macroscopic quartz crystals.
The light purplish material also showed 2 kinds of crystal habit, sharper terminated elongated crystals in sheath-like formations, and almost pseudocubic form aggregates, quite interesting.
The FOV's here are 0.8mm. Both reflected and transmitted plane-polarised light was used, thus the colour reproduction is not quite true.
11th Oct 2017 10:27 UTCOlav Revheim Manager
It would be really nice if you upload a picture of the full size specimen with these photos as child photos to this locality https://www.mindat.org/loc-270940.html
I think these photos are really educational and interesting
Olav
12th Oct 2017 08:22 UTCJoel Dyer
Do you mean I would add as the main photo the full-specimen picture, then the above two as child photos, perhaps along with 1-2 Raman analytical data child photos?
Cheers,
Joel
12th Oct 2017 12:47 UTCOlav Revheim Manager
That would be perfect!
Thanks
Olav
12th Oct 2017 22:26 UTCJohn Oostenryk
Oh Please DO!
I find this material very interesting- and your imagery would be a great aid to conveying/explaining the current description!
For a humorous aside~(and nothing else!) The appearance of the crystalline surface- immediately brings to mind a common formation in the "Keokuk geode region" sedimentary geodes.
A thin layer of chalcedony overgrowth of the quartz crystals. These are like an inside-out one... in MICRO scale :)-
Best Regards!
~JohnOostenryk
Assistant Curator,
Fryxell Geology Museum
12th Oct 2017 22:47 UTCOwen Lewis
If one of you guys that have some break off a a piece or two of the partly transparent spheroids (likely quartz), You can test for:
- Fracture lustre.
- Optic character
Get a piece polished optically flat. and you can get the (different) RIs for both quartz or chalcedony specimens and sort them out with confidence. I would not want to rely on hardness and SG testing in this instance.
13th Oct 2017 03:24 UTCAlfredo Petrov Manager
13th Oct 2017 13:09 UTCOwen Lewis
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Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: May 11, 2024 15:09:33