Log InRegister
Quick Links : The Mindat ManualThe Rock H. Currier Digital LibraryMindat Newsletter [Free Download]
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsThe Rock H. Currier Digital LibraryGeologic Time
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsClubs & OrganizationsMineral Shows & EventsThe Mindat DirectoryDevice SettingsThe Mineral Quiz
Photo SearchPhoto GalleriesSearch by ColorNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography

PhotosToday's quiz: Arsenopyrite, lӧllingite or ? From ?

2nd Feb 2012 20:35 UTCModris Baum 🌟 Expert

08138560016049297454721.jpg
Click on title at top of page to see the photo.


This is a bit embarrassing:


I have no recollection of when, how or why I got this. I'm not even sure if it's arsenopyrite, lӧlingite or something more exotic.


And I have no clue regarding location - other than that it does not look like anything from the places I have collected at: Franklin (area), MSH, PA or Maine.


Given the recent spectacular success of my last few queries, I'm expecting a resolution as soon as I click send ;-)


Thanks - Modris

2nd Feb 2012 22:56 UTCAlfredo Petrov Manager

Reminds me a bit of dyscrasite.

2nd Feb 2012 23:38 UTCModris Baum 🌟 Expert

Hi Alfredo,


I see what you mean - and dyscrasite would be cool.


But where the heck could I have gotten it? I strongly suspect (but don't recall) that some local collector gave it to me. Of course he could have found it anywhere. But I don't see any dyscrasite localities listed for US or Canada.


Note: The "color" is very silvery - just like lollingite and arsenopyrite.


I suppose I could have bought it and forgotten - but it's not the kind of thing I'd normally buy.


Modris

2nd Feb 2012 23:47 UTCCraig Mercer

Photo's not that great, but reminds me of Tremolite.


Goodluck,

Craig.

3rd Feb 2012 00:36 UTCModris Baum 🌟 Expert

Hi Craig,


I think the problem is that the reflections make it look white, whereas my intention was to capture the silvery metallic luster.

Also, the xl is still patially embedded so the shape may not be clear.


I replaced the photo with one of a smaller xl. (This was already there as a stereo child photo, but maybe this mono shot is more useful in this case.)

I put the original parent as another child photo.


Modris

3rd Feb 2012 04:00 UTCCraig Mercer

Hi Modris,


Yes you are correct, I was seeing it as white.


After looking at the other photo's, I think you maybe correct about it being Arsenopyrite, as far as look goes anyway.


My guess now, just to give you another avenue would be Pearceite.


Goodluck my friend,

Craig.

3rd Feb 2012 04:37 UTCAlfredo Petrov Manager

Yes, under this new light angle it does look more like an arsenopyrite.

3rd Feb 2012 05:00 UTCModris Baum 🌟 Expert

OK - thanks guys.


But I have a feeling I'll never know from where. No big deal.


Modris

3rd Feb 2012 09:56 UTCChristian Auer 🌟 Expert

Don`t give up that quick, its a nice specimen :-)

I worked a bit on the pic, hope it fits and help others by the ID.

3rd Feb 2012 10:02 UTCPeter Andresen Expert

Well, it did remind me of arsenopyrites I've collected at Sagåsen quarry, occuring in analcime matrix with minor calcite, mine wasn't that nice though... Have you traded with Tomas Husdal?


Peter

3rd Feb 2012 10:13 UTCCraig Mercer

Just a stab, but I have seen similar Mexican specimens also.

3rd Feb 2012 14:19 UTCReiner Mielke Expert

If you place a small piece ( approx. 0.1mm) in concentrated nitric acid, if it is arsenopyrite after about 12 hours or less you will have a pseudomorph of fine grained yellowish sulphur left behind. If it is loellingite you will find a lump or pile made up of relatively coarse grained white-grey crystals of arsenic oxide.

3rd Feb 2012 16:21 UTCModris Baum 🌟 Expert

Thanks folks!


Peter - interesting suggestion. I haven't traded with Tomas but I did trade a bit - years ago - with a German collector with a great interest in Norway.


Also interesting regarding the analcime. When I was looking at the white stuff in the matrix I was saying to myself "Gee, this looks familiar." I decided it must be quartz, but now that you mention it, it really looks more like analcime. It would be ironic if I actually did find this myself - at MSH. But for MSH this would really be killer arsenopyrite!


Reiner - thanks for the tip. I don't have any nitric acid but I'll see if I can get some. Sounds like a very useful test.


Modris

3rd Feb 2012 17:55 UTCModris Baum 🌟 Expert

Chris,


Looks like you sharpened the photo and/or increased contrast? Did you use a "global" tool (like "auto levels") or seperate steps?

On my monitor your version looks too blue/purple. But mine now looks too green. The truth may lie somewhere in the middle.


Modris

3rd Feb 2012 18:45 UTCChristian Auer 🌟 Expert

No I used separate steps with Nikon Capture and yes its still a bit too purple also here.

3rd Feb 2012 19:29 UTCModris Baum 🌟 Expert

Peter,


I tried measuring the average specific gravity of the samples using a modified Archimede's method.


I used a kitchen scale that measures only in ounces and is probably accurate to 0.1 oz at best so my results are probably not definitive.


The samples weigh 1.3 oz; an equivalent amount of water about 0.6-0.7 oz - say 0.65 oz.


So the specific gravity could range from a high of 1.4/0.55 = 2.55 to a low of 1.6.


The low number is not plausible, but even the high number seems to exclude quartz (especially given the mica inclusions - ~2.8)


But the the range does cover analcime (2.27) "comfortably".


Reiner,


Turns out I may have some nitric acid left over from more ambitious days (i.e. before I burned holes in my shirts).

It's been sitting for many years, safe and sound, in a ground glass stoppered bottle.


But I can't get it open. Heating with hot water hasn't helped so far. Any suggestions?


Also - is there an easy way to tell if it's nitric or hydrochloric? I neglected to label it. The color is quite yellow - but maybe I already used it on something.


Modris

3rd Feb 2012 22:00 UTCReiner Mielke Expert

Those glass stoppers can really seize on. Last time that happened I had to use pliers and turned it while pulling up to loosen it, hopefully it will turn before breaking. Wearing rubber gloves while you do it would be a good idea. Maybe soak it in water overnight as well first to dissolve some of the deposits that have probably seized it on. The smell will tell you what it is, but don't stick your nose up to it, waft some towards you with your hand. A sharp acid smell is HCL a more fresh smell ( hard to describe) is nitric acid.

3rd Feb 2012 22:16 UTCKeith Compton 🌟 Manager

Modris

If you have kept the acid after it has been used and you think it contains contaminants I would not use it. I would suggest that you dispose of it appropriately and purchase somw fresh acid for you tests

Cheers

3rd Feb 2012 22:18 UTCModris Baum 🌟 Expert

For anyone who still cares, I posted a new version of the original photo.


This time I picked away a bit more of the matrix and concentrated on trying to show the shape of the xl rather than trying to show the silvery luster.

There are still some areas that are close to "blowouts" (i.e. white looking) but mostly not.


With this exposure, the background also looks more natural (lighter) because it wasn't as badly underexposed as before.

(However, the stuff here looks more like feldspar than the "analcime" on the rest of the specimen.)


Modris


Reiner


Thanks much. If I can't get the stopper unstuck I guess I'll have to get some from Ward's - 500ml minimum (yuck)

3rd Feb 2012 22:35 UTCPeter Andresen Expert

Matrix really looks alkaline... Both arsenopyrite and löllingite occure in our alkaline pegmatites, and there is no way to distinguish them visualy is my excperience. It's getting darn difficult to get chemicals in Norway these days, but I'll try to get some nitric-acid, would be fun to test out... :-)


Was it Wilfried you swaped with (if it is, it's not the Sagåsen material I thought of... it was found by Husdal in 2009 or 10, and it was also rich in bertrandite...)?

3rd Feb 2012 22:48 UTCModris Baum 🌟 Expert

Hi Peter,


Yes it was Wilfried. But I don't think it was from him. All of his stuff was carefully labeled and I have tried to keep it carefully separate from everything else. Of course I do screw up - regularly! Anyway it was around 1995.


Regarding the matrix, after a more careful look, it seems that the arsenopyrite/lӧllingite as well as the mica is confined to bands that are mostly feldspar (?), whereas the adjacent analcime is pretty barren except for the one lone black prismatic xl.


Given that, it's not out of the question that it's from MSH. But the arsenopyrite/lӧllingite would be way better than anything I have seen from there . I can't understand why I would have dumped it in a "miscellaneous" box if I knew it was from MSH? But I have zero recollection of even seeing this specimen before. Maybe I just never looked at it with a scope!


Modris

3rd Feb 2012 23:53 UTCMark J. Sigouin

About three years ago I collected a silvery mineral from Franklin that I thought was Lollingite, Galena, or Arsenopyrite. It was really dense and heavy. Some specimens were hand sized plates. They came from an augen in the Franklin Marble forming the walls of the Passaic Pit, Sterling Hill Mine.


It would have been a huge bonanza if it was Lollingite. I finally had a piece analyzed and it was Galena. Still a nice find.


The attached picture is from two small pieces I could locate without having to ransack the basement. Note the foliated habit expressed by the shiny surfaces. There is no real cubic aspect to the galena in these specimens. They have a more tabular structure. Unfortunately Lollingite and Arsenopyrite also can have a tabular or compressed structure. Look up the minerals, and look at the various crystal structures shown.


The matrix may be calcite. More particularly, Franklin Marble. Check and see if it fluoresces red brightly under short wave fluorescent light or perhaps faintly under a regular black light. If it does it is probably from Franklin. But then, if they don't fluoresce they may still be from that area, just not from the vicinity of the zinc ore.


You might want to look at Dunn's description of arsenopyrite from the Franklin Mining District on this web page.


http://franklin-sterlinghill.com/dunn/ch21/arsenopyrite.stm


In the description, he mentions chevron structure which these crystals seem to exhibit.


Good Luck,

Mark

4th Feb 2012 00:49 UTCModris Baum 🌟 Expert

Hi Mark,


Interestingly enough, I have some samples of galena from the Passaic Pit that are very similar to yours.


In fact, I was going to post some photos because there aren't any galena photos from the Pit on Mindat and because some of the samples have a very beautiful iridescence. Also, some of this stuff is the host for the cerussite at SH. (I'll probably post in a couple of days - once I'm done with a few more micros.)


Regarding the material we have been discussing: It's pretty clear to me now that there is a lot of analcime in the matrix which pretty much rules out Sterling Hill. There is a weak cherry red fluorescent response. But albite at MSH (etc.) has a similar response and there seems to be some feldspar in the matrix as well.


I did test for calcite with HCl and got some bubbles - but it didn't last very long. Can't be very much there.


As for it being arsenopyrite - that seems likely now. But I want to do the test for lӧllingite first before declaring victory.


Thanks for your interest - Modris

4th Feb 2012 14:54 UTCWilfried Steffens

Hi Modris,

sorry for the delay, but I just now found time to get down tot he basement and to check my specimens. Some Tuften (aka AS Granit) specimens look a lot like yours, but they are from recent years, maximum 3 years ago. So too late for our swap.

It may (or may not) be an arsenopyrite from Björndalen Quarry in Tvedalen - a swap in 1995 might fit with the specimen being a few years older. There's a comparable one in my collection (which is not the counterpart of yours, though). Unfortunately I do not remember after all these years, what I sent you. So this probably doesn't help either.

Take care

Wilfried Steffens

4th Feb 2012 16:27 UTCModris Baum 🌟 Expert

Hi Wilfied


Good to hear from you. Thanks for the response.


As I mentioned, I have kept your stuff separate. So it would have to have been one of those "senior moments". You know: "Let's see what this is. Oh wait, the phone is ringing. ... Now where was I? Hmm - couldn't be important." But then what happened to your label?


Anyway - I'm now thinking that it's from MSH after all. But I don't think I'll ever be able to prove it.


Horváth does mention arsenopyrite to 1.5 cm from marble xenolith at MSH. But this isn't from that environment and I can't really place it in any of the "typical" MSH environments that I'm familiar with.


Best regards - Modris

21st Feb 2012 01:58 UTCModris Baum 🌟 Expert

Well - I did my "homework". But to no avail.


The acid I had in the ground glass stoppered bottle is just HCl (probably concentrated).

After about 11 hours, the grain of arsenopyrite/lӧllingite has done absolutely nothing in the stuff.

But the acid is happy enough to munch on calcite - even after 20-30 years.


So now I have to decide if I really want to get 500 ml of nitric acid. (Or if I even can. Maybe you have to be a school or some such?)


Modris
 
Mineral and/or Locality  
Mindat Discussions Facebook Logo Instagram Logo Discord Logo
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © 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: March 29, 2024 06:39:05
Go to top of page