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PhotosToday's quiz: Arsenopyrite, lӧllingite or ? From ?
2nd Feb 2012 20:35 UTCModris Baum 🌟 Expert
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
2nd Feb 2012 23:38 UTCModris Baum 🌟 Expert
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
Goodluck,
Craig.
3rd Feb 2012 00:36 UTCModris Baum 🌟 Expert
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
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
3rd Feb 2012 05:00 UTCModris Baum 🌟 Expert
But I have a feeling I'll never know from where. No big deal.
Modris
3rd Feb 2012 09:56 UTCChristian Auer 🌟 Expert
I worked a bit on the pic, hope it fits and help others by the ID.
3rd Feb 2012 10:02 UTCPeter Andresen Expert
Peter
3rd Feb 2012 10:13 UTCCraig Mercer
3rd Feb 2012 14:19 UTCReiner Mielke Expert
3rd Feb 2012 16:21 UTCModris Baum 🌟 Expert
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
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
3rd Feb 2012 19:29 UTCModris Baum 🌟 Expert
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
3rd Feb 2012 22:16 UTCKeith Compton 🌟 Manager
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
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
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
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
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
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
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
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
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
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