We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences


Spanish message board






Newest topics and users posts
03 Aug-12:44:56 Re: collection of firmo espinar (Firmo Espinar)
03 Aug-09:47:23 James sowerby's illustrations (James Catmur)
02 Aug-21:10:46 Re: collection of sante celiberti - a mineralogical trip through italy (Don Lum)
02 Aug-20:02:55 Re: stay at home - coronavirus / covid-19 (Vic Rzonca)
02 Aug-19:58:19 Re: a mineralogical trip through the states of usa - idaho (Rweaver)
02 Aug-15:35:24 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
02 Aug-15:31:31 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
02 Aug-13:19:26 Re: collection of sante celiberti - a mineralogical trip through italy (Jfc035)
02 Aug-13:18:08 Re: collection of sante celiberti - a mineralogical trip through italy (Jfc035)
02 Aug-13:07:30 Re: don lum collection (Don Lum)
02 Aug-12:48:31 Re: collection of sante celiberti - a mineralogical trip through italy (Mathias)
02 Aug-12:46:48 Popular minerals - wurtzite with galena from the Ánimas mine, bolivia (Jordi Fabre)
02 Aug-11:36:19 Re: to test or not to test (Peter Megaw)
02 Aug-05:30:19 Re: to test or not to test (Alfredo)
01 Aug-22:33:24 Re: don lum collection (Don Lum)
01 Aug-16:19:36 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
01 Aug-12:44:51 Re: stay at home - coronavirus / covid-19 (Philippe Durand)
01 Aug-11:55:33 Re: collection from dany mabillard (Dany Mabillard)
01 Aug-10:40:56 Re: stay at home - coronavirus / covid-19 (Dany Mabillard)
01 Aug-01:52:32 Re: is this calcite or dolomite (Matt_zukowski)
31 Jul-22:42:56 Re: is this calcite or dolomite (Xdxucn)
31 Jul-20:52:02 Re: is this calcite or dolomite (John Betts)
31 Jul-17:04:32 Popular minerals - large fluorite from la viesca mine, asturias, spain (Jordi Fabre)
31 Jul-15:42:16 To test or not to test (Bob Harman)
31 Jul-15:07:27 Re: the mineral collecting history of the 79 mine, gila county, arizona, usa - (33) (John Cornish)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
70674


The time now is Aug 03, 2020 12:48

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
Opaque black Quartz, Locality info/matrix info?
  Goto page 1, 2  Next
  Index -> FOR BEGINNERS: What is it? Where is it from?
Like
6


View previous topic :: View next topic  
Author Message

briggzi31




Joined: 13 Jul 2020
Posts: 5
Location: Seattle

View user's profile

Send private message

PostPosted: Jul 13, 2020 17:26    Post subject: Opaque black Quartz, Locality info/matrix info?  

Hey guys, this is my first post so don't beat me up too badly! I've been collecting since the first grade and now am currently an undergrad at U of W, but just recently have been going through my collection and making proper labels.

Anyway, I got this a couple years ago without a label and don't know the locality. I am hoping a good samaritan can help me out.

This quartz is opaque (about as opaque as black obsidian), which I know is unusual for quartz specimens. When held up to a light, the only transparency occurs at the edges just like an obsidian specimen. The luster is kind of dull, and I would say it is comparable to the luster typically found on sulfur crystals.

The matrix is grainy, and looks to be a conglomerate. Within the matrix there are small crystals which exhibit rhombohedral habit, and I am wondering if those are something like calcite/dolomite?

After a brief search on Mindat, I was wondering if Khoroshiv, Zhytomyr Oblast, Ukraine was a viable option? I was unable to find a quartz crystal on matrix to confirm, but the luster and opaqueness of the quartz matches mine. Also some of the matrix might be microcline, which would match a specimen from this locality. Tell me if I'm wrong!! Any suggestions for a proper label are welcome.

Thanks in advance!
Sam



IMG_2291.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
Front/Crystals
 Viewed:  1785 Time(s)

IMG_2291.JPG



IMG_2292.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
Upside down/Matrix. This matrix appears more green than in real life. The correct color should be slightly more yellow/brown.
 Viewed:  1788 Time(s)

IMG_2292.JPG



IMG_2299.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
What I think could be microcline is surrounding the crystal in the front/center of the photo
 Viewed:  1784 Time(s)

IMG_2299.JPG



IMG_2298.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
Best example of the small crystals with rhombohedral habit. Sorry for my lack of a macro lens!
 Viewed:  1784 Time(s)

IMG_2298.JPG


Back to top
Reply to topic Reply with quote
Like
   

Bob Harman




Joined: 06 Nov 2015
Posts: 701
Location: Indiana


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 13, 2020 17:35    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

I would guess some locality in China.
Wherever your example is from, the quartz looks like it has been irradiated; in my opinion, that is not natural smoky quartz. BOB
Back to top
Reply to topic Reply with quote
Like
   

SteveB




Joined: 12 Oct 2015
Posts: 136
Location: Canberra

View user's profile

Send private message

PostPosted: Jul 13, 2020 19:49    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Bob Harman wrote:
I would guess some locality in China.
Wherever your example is from, the quartz looks like it has been irradiated; in my opinion, that is not natural smoky quartz. BOB


Can I ask what about the quartz indicates irradiated to you? I’ve had a single large crystal in my collection since the late 1970’s which is also a very solid black I got from a science teacher neighbour so no known location (not that I’m interested in trying to work it out, it may have come from an educational supplier though my neighbour travelled often bringing back specimens.

Original poster: I suggest you apply a drop or two of hydrochloric acid to your specimen. Somewhere in the underside matrix to help determine if it could contain calcite minerals, Also a drop on the quartz where its dull, may indicate if its surface coated with calcite. Might help with your location quest. But your talking about common minerals here so gather as many facts with data gathering you can from your specimen. Surely the UW geology dept has staff willing to help and possibly have tools like an XRF to help with chemical analysis which is vital for accurate location confirmation.
Back to top
Reply to topic Reply with quote
Like
   

Joseph DOliveira




Joined: 29 Jan 2012
Posts: 234
Location: Hanmer, Ontario


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 13, 2020 20:31    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Here is an example of the Ukraine "morion" quartz crystals. The quartz crystals are large and quite black with a dull outer appearance and they are not artificially irradiated. Unfortunately it does not have any matrix. It is approximately 8 inches long and about 2 inches in diameter.


collection 061 (2).JPG
 Mineral: Quartz
 Locality:
Khoroshiv (Volodarsk-Volynskii), Zhytomyr Oblast, Ukraine
 Description:
 Viewed:  1726 Time(s)

collection 061 (2).JPG



_________________
Joseph D'Oliveira
Hanmer, Ontario
Canada
Back to top
Reply to topic Reply with quote
Like
4
   

briggzi31




Joined: 13 Jul 2020
Posts: 5
Location: Seattle

View user's profile

Send private message

PostPosted: Jul 13, 2020 21:48    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Thank you all for responding, and for your help!

@Bob The fact that it could be irradiated never crossed my mind, and I would be remiss to find out that it truly is.

@Steve I will have to acquire some HCl and test it. I am assuming I am looking for bubbles? Also wondering how just regular vinegar would be for now as i don't have any HCl on hand?

@Joseph Wow, you're specimen is beautiful. Obviously, my quartz points are much smaller, and I think it is unlikely that this came from Ukraine (although not impossible).
Back to top
Reply to topic Reply with quote
Like
   

SteveB




Joined: 12 Oct 2015
Posts: 136
Location: Canberra

View user's profile

Send private message

PostPosted: Jul 14, 2020 00:18    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Yes white vinegar can be used as an acid test. Yes you are looking for bubbles, though it could be a fast reaction or a slow depending on the calcium amount present. I’m no expert but vinegar acidity I assume will differ depending on brand plus its NOT a standard nor a measurement indicator. Hydrochloric acid is cheaply available In most countries. I get mine at my local hardware store but my local chemists also have it. Other acids are more controlled and difficult to get. You only need a single drop to test and must be used in a well ventilated area as the vapor if inhaled WILL damage your lungs and can irritate eyes, plus it’ll be corrosive on any iron based metals in the area. Typically geologists dilute to 10% and have in a small plastic bottle that has a dropper opening. That way is safe enough for them to carry and use in the field. Again you should be able to get someone at your university to put a drop on your specimen for you in their lab if you’re concerned. They’ll have something on hand to neutralize and wash it from your specimen too. With collected and display specimens, try to test in a representative and inconspicuous location. Typically several such spots and observe the reaction, is it instant or take a few minutes for something to happen? Or does nothing occur? Are lots of bubbles produced or only a little? Observe and record, Of course on something like a glassy flat surface of a nice calcite crystal you can expect the acid to mark the surface permanently. Quartz should have zero reaction, but if another mineral has coated the quartz surface it may.

The matrix is not a pure mineral, its a rock (a combination of minerals) so the amount of acid reactive minerals will differ from location to location and it may help you and others to eliminate possibilities. Also unless you collected the specimen yourself from the ground you can’t know for certain if the specimen hasn’t already been submerged in acids for a period of time in order to remove ugly matrix or coatings/stains so its reaction amount may not be accurate to represent that matrix. Unless you can break off a piece to expose the inside of the matrix, giving you a fresh unmolested surface to test on. If you can get the help of a chemistry prof at UW you could do the same test with nitric and sulphuric acids too and they can explain you you what the results mean chemically (high/low amount of possible minerals etc) its all data that helps. No single test will tell you with 100% accuracy nor will posting a couple of photos to a forum. Testing is vital to identification/elimination. Since you are at UW you’d be wise to speak to teachers there in chemistry and geology who can help you with data collection methods, testing and examination. You’ll learn much which will help with other specimens in the future. The process of mineral identification involves a LOT of steps in a complex flowchart, browsing Mindat is not one of them. I hope you get a satisfactory answer, elemental analysis of the primary mineral(s) does differ with locations and is used as a fingerprint to confirm source location, and even ownership in certain circumstances. Some of the equipment needed to do this may be at your university, but once you’ve left you are likely to never ever have an opportunity to ask for help to test a specimen. The equipment is expensive and what few models available to consumers only test for a small subset of the periodic table of elements so they can help but still have limitations. So make use while you have the chance, don't be fool to think the internet is the answer to everything.
Back to top
Reply to topic Reply with quote
Like
   

briggzi31




Joined: 13 Jul 2020
Posts: 5
Location: Seattle

View user's profile

Send private message

PostPosted: Jul 14, 2020 01:03    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Wow, thank you for such a detailed thorough response, Steve! I have learned quite a lot just from the first few hours on this forum. I posted on this forum as a first step, and I am glad that I did, because you guys were able to point me in the right direction.
I will have to do some digging in to which professors to get in touch with, as Chem/Geology are departments of my school that I am not well versed in, being a math major. About the different testing instruments, I am sure that we have top-of-the-line everything being a "R1" research school, sitting near the Cascades on the subduction zone and having 50,000 students and all. Can't wait for the pandemic to end so that I can not only learn in person, but also so that I can use my school's resources again.
Best,
Sam
Back to top
Reply to topic Reply with quote
Like
   

Amir Akhavan




Joined: 01 Dec 2009
Posts: 51
Location: Hamburg

View user's profile

Send private message

PostPosted: Jul 14, 2020 03:21    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

It looks like a specimen from a pegmatite, smoky quartz + microcline, covered by chabazite (typical slightly skewed "cubes") and its common associate stilbite.
Nevertheless, doing a "fizz test" is always a good idea.

That mineral association is common in pegmatites and in alpine type fissures, but the way quartz and feldspar are intergrown in the matrix looks more like a pegmatite specimen to me.
Very hard to pinpoint the locality.
China is a good guess, could be irradiated or natural.

_________________
Amir C. Akhavan, Hamburg, Germany
Back to top
Reply to topic Reply with quote
Like
   

Volkmar Stingl




Joined: 23 Sep 2012
Posts: 150
Location: Innsbruck


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 14, 2020 03:31    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Amir Akhavan wrote:

Very hard to pinpoint the locality.
China is a good guess, could be irradiated or natural.


I agree. My first guess was also smokey quartz with chabazite, which leads me to the Chinese granite and pegmatite quarries around Wulian, Rizhao Prefecture (as a possibility). The black quartzes from there are naturally irradiated by the U-content of the rock.

Volkmar
Back to top
Reply to topic Reply with quote
Like
   

SteveB




Joined: 12 Oct 2015
Posts: 136
Location: Canberra

View user's profile

Send private message

PostPosted: Jul 14, 2020 03:33    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Well, I suggest you take your specimen in one day, find where a geology/chemical class is and just pop in after the session and say “hello” to the instructor for a start, let them know you’re not in their class and you’re trying to figure out where it came from and would like their help with testing options that may help build up a good picture. Whoever you speak to should be able to give some assistance and/or point you to the right member of faculty. Just be polite and patient, start by asking when they have time to talk to you, common sense really. Teachers are often not given the respect they deserve and are passionate about the subjects they teach so typically happy to spare some time for others interested too. It's also why dedicated forums like this are helpful, we share a common interest. However this is a hobby that requires practical skills so if you get in touch with someone at the university, pay attention to the tools they use for testing and examination and show an interest in how they use them. Ask questions but don't bug them. Their time is limited so be thankful for any they can spare. There are also local lapidary or rockhound clubs that could help to with getting started on quest. It's really going to be up to you how much effort you are willing to put in. The black quartz is in a matrix that appears to contain another mineral of yellow crystals, the whole matrix is not a single rock that will answer things on its own. Identifying that mineral gives you a habitat association that will greatly narrow down location possibilities. Careful magnified examination of the matrix may reveal to you other minerals present that may be identifiable giving you more associations. Like I mentioned earlier though I think spectrometry is the only possible way to pin it down. Getting the chemical signature and being able to match that to the signature of likely location is very expensive and may not be worth the effort. There are labs that will analyze mineral samples which you need to prepare yourself and likely to cost over $500. Plus it needs to be the right type of analysis and report to compare to whatever location data you can source. It's next to impossible to start with a single specimen and just say where its from, it takes time and testing to first identify without doubt the minerals in the sample. Almost every crystal-forming mineral can be found naturally in almost every color and many minerals share similar enough crystal formation to make visual identification tricky. Knowing exactly where a specimen comes from helps in identifying it, not the other way around.
Back to top
Reply to topic Reply with quote
Like
   

Gagat Minerals




Joined: 08 Nov 2017
Posts: 38
Location: Greater London


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 14, 2020 03:35    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

- for me Tongbei- Fujian Province, China
Back to top
Reply to topic Reply with quote
Like
   

Volkmar Stingl




Joined: 23 Sep 2012
Posts: 150
Location: Innsbruck


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 14, 2020 03:47    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

I think, there are also some stilbites at the back side. Stilbite and chabazite are not known from Tongbei, but from Wulian!
Back to top
Reply to topic Reply with quote
Like
   

Gagat Minerals




Joined: 08 Nov 2017
Posts: 38
Location: Greater London


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 14, 2020 05:00    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Volkmar, I never have been in China because of the minerals, but I'm quite regularly checking zeolites on the 'China Neolithic' web page and this guy is updating new finds, so not only stilbite (with a new research indicate also possible stellerite ), chabazite and laumontite, and heulandite from last year too.
Back to top
Reply to topic Reply with quote
Like
   

Volkmar Stingl




Joined: 23 Sep 2012
Posts: 150
Location: Innsbruck


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 14, 2020 11:59    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Gagat Minerals wrote:
Volkmar, I never have been in China because of the minerals, but I'm quite regularly checking zeolites on the 'China Neolithic' web page and this guy is updating new finds, so not only stilbite (with a new research indicate also possible stellerite ), chabazite and laumontite, and heulandite from last year too.


I've never heard of. Can you post the link to this web page, please?
Back to top
Reply to topic Reply with quote
Like
   

briggzi31




Joined: 13 Jul 2020
Posts: 5
Location: Seattle

View user's profile

Send private message

PostPosted: Jul 14, 2020 18:33    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Update: I got some HCl from the hardware store and performed an acid test on the matrix as well as the quartz crystals themselves. There was absolutely no effervescence, even when viewed with a 10x jewelers loupe. I also tested some calcite and dolomite so that I could compare their reactions and so I am 98% sure that the rhombohedrons nor anything else on this specimen is calcite. This leads me to believe that the rhombohedrons are chabazite as many of you have suggested. Is there any other AT HOME tests that I could do to confirm my hypothesis? I don't think that a streak test is viable because they are too small :(

I am starting to believe that it is highly likely that this is from China. I am still reluctant to believe that it is irradiated, but it still might be. In all honesty, labeling the locality as China (although very broad) is good enough for me for now until I can get into a lab and do some tests with a geology/chem prof. In the meantime, I have included some photos using my makeshift macro-lens (shooting my phone's camera lens through a jeweler's loupe) to try to give you guys some better pictures to work with.

Thank you all for your help, and welcoming me into this forum!
Sam



IMG_2311.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
This is the same rhombohedron on the matrix that I circled in my first post.
 Viewed:  1422 Time(s)

IMG_2311.JPG



IMG_2312.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
Another matrix photo
 Viewed:  1419 Time(s)

IMG_2312.JPG



IMG_2313.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
Another matrix photo
 Viewed:  1420 Time(s)

IMG_2313.JPG



IMG_2314.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
I didn't notice this crystal on the black quartz before. Maybe a spessartine garnet?
 Viewed:  1420 Time(s)

IMG_2314.JPG



IMG_2315.JPG
 Mineral: Quartz
 Locality:
[unknown locality]
 Dimensions: 8cm * 6cm * 4cm
 Description:
Another matrix photo
 Viewed:  1421 Time(s)

IMG_2315.JPG


Back to top
Reply to topic Reply with quote
Like
1
   

Volkmar Stingl




Joined: 23 Sep 2012
Posts: 150
Location: Innsbruck


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 14, 2020 22:59    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Clearly chabazite and stilbite in the matrix. The small crystal on the black quartz is also quartz (2nd generation).
My guess is still Wulian.

Volkmar
Back to top
Reply to topic Reply with quote
Like
   

James Catmur
Site Admin



Joined: 14 Sep 2006
Posts: 701
Location: Cambridge


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 15, 2020 14:44    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

briggzi31 wrote:
about as opaque as black obsidian


I have Obsidian that is totally transparent (although my best piece was stolen)
Back to top
Reply to topic Reply with quote
Like
   

Riccardo Modanesi




Joined: 07 Nov 2011
Posts: 546
Location: Milano

View user's profile

Send private message

PostPosted: Jul 16, 2020 03:04    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Hi to everybody! James, yes, transparent obsidian DOES exist, it's called "apache tears", small spheres in perlite, from Arizona, USA and Mexico (I don't remember the proper locality anymore, I apologize).
Greetings from Italy by Riccardo.


James Catmur wrote:
briggzi31 wrote:
about as opaque as black obsidian


I have Obsidian that is totally transparent (although my best piece was stolen)

_________________
Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo.
Back to top
Reply to topic Reply with quote
Like
   

Gagat Minerals




Joined: 08 Nov 2017
Posts: 38
Location: Greater London


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 16, 2020 03:29    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Volkmar Stingl wrote:
I've never heard of. Can you post the link to this web page, please?


you need to use Google search: China Neolithic Minerals; (btw - this person have not a big clue about minerals so be patient and don't treat all descriptions too serious :)).
regards
Back to top
Reply to topic Reply with quote
Like
   

Volkmar Stingl




Joined: 23 Sep 2012
Posts: 150
Location: Innsbruck


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 16, 2020 06:06    Post subject: Re: Opaque black Quartz, Locality info/matrix info?  

Hi,

Now I found it. When checking the chabazite pictures, I must admit, they look also similar, except one difference: Most of the chabazite from Tongbei is combined with clear quartz, only few with smokeys (additionally, I am amazed at the missing spessartines). So I agree, it could be a possible source. Additionally, Ottens mentions few chabazites from pegmatites near Babu, Guangxi Zhuang, in his book from 2008.
So I have to relativise my statement, the piece could be also from other places than Wulian.

Volkmar
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> FOR BEGINNERS: What is it? Where is it from?   All times are GMT - 5 Hours
Page 1 of 2
  Goto page 1, 2  Next  

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2020


Powered by FMF