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Need help Identifying my rock

Posted by Chris Silva  
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Chris Silva May 04, 2018 06:31PM
Hello everyone i can’t seem to find an answer with figuring what i may have found your help is appreciated if pictures can’t be seen I’ll email them thanks



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Chris Silva May 04, 2018 06:35PM
If anyone needs to know the colors of my rock it’s silver with bluish purple tint and very beautiful to look at. It’s not magnetic and it’s heavy we chipped a piece off striking It very hard with a hammer
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Chris Silva May 04, 2018 06:36PM

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Volkmar Stingl May 04, 2018 07:05PM
This is artificial, some kind of alloy?
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Kevin Conroy May 04, 2018 07:20PM
I agree with Volkmar, not a natural mineral. Slag maybe. Where did you find them?
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Reiner Mielke May 04, 2018 07:57PM
Looks like a Si-Mn alloy.
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Chris Silva May 04, 2018 08:23PM
Found in CT on a construction site i believe
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Chris Silva May 04, 2018 08:35PM
I looked up most elements and the only thing close is silicon but it’s not quite the same. I’m waiting to see a specialist at Peabody Museum too
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Reiner Mielke May 04, 2018 09:16PM
Yes that is because it is alloyed with manganese which makes it heavy.
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Chris Silva May 04, 2018 09:33PM
I sent you a pm I’m not sure if it has other elements someone said he saw a little iron in there today so I’m not too sure about it. I looked up all your suggestions online and nothing is 100% match
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Greg Simmons May 08, 2018 04:54AM
I have a piece that has 3-4 different minerals on it. I think I know what they are but would appreciate some help making sure. I think it is quartz after chrysocolla with baryte but there is a 4th that I'm not sure about. It was purchased at Tucson Mineral and Gem World a couple of years ago. The way my wife tells it, she was about to check out with a couple of purchases for me and two teenagers walked in with a suitcase full of rocks and asked the owner if he buys rocks. He said he did and made them an offer. This was one of the pieces. my wife liked it and made him an offer that he agreed to. Based on that and looking at some photos on Mindat, it is very similar to this piece: https://www.mindat.org/photo-172238.html in terms of color, matrix, and crystals. I suspect it is from the same or near location.

This is the full piece. it is 6.5 inches by 5 inches. It weighs about 3 lbs.


Originally I thought it was stilbite but I don't think that makes sense but the crystals also look like hemimorphite like this: https://www.mindat.org/photo-4112.html and the quartz has tiny rice-like crystals sprinkled all over it shaped like this: https://www.mindat.org/photo-66236.html

Any insight would be appreciated

Greg,
This is one of the ones I think is baryte. There is a cluster of them in a vug and about a dozen single crystals or small clusters around the piece. All of the crystals are colorless and very clear but have this pinkish inclusion on just the edges of the crystals. They are sort of triangular in shape.
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Kevin Conroy May 08, 2018 05:27AM
I think your specimen comes from somewhere in India, and mainly has zeolite minerals. The last photo is likely huelandite (triangular crystal), the elongated whitish crystals stilbite, and the greenish ones fluorapophyllite. To make an educated guess on the large crystal in the middle photo I would need a few more angle views of the crystal.



Edited 1 time(s). Last edit at 05/08/2018 02:11PM by Kevin Conroy.
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Gregg Little May 08, 2018 05:55AM
Would the large crystal in the middle photo be stilbite as well; the a axis pointing to the upper right corner? Like kevin says more/better pictures.
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Greg Simmons May 08, 2018 06:44PM
Thanks guys. I did take more pix but it only let me add three so I'll post some more tonight. Originally I thought as you did, Kevin, that it was Stilbite. The "green" crystals are actually clear but on a green crust, hence why I thought Chrysocolla with quartz over top, like the mindat images I linked to. It doesn't follow any of the crystal habits of apophylite, that I've seen before anyway. The color is a lot more blue than I've seen before too. Then, as I was looking at images of hemimorphite I saw some that some looked just like the large white one I assumed was stilbite AND also the tiny ones that looked like rice. So now you see why I'm confused and started to question what it really was. The large white crystal and the "rice" ones look like both stilbite and hemimorphite. The triangular ones look like heulandite and baryte. thinking strongly that the blue-green was chryocolla with quartz, the stilbite wasn't making sense to me.

Anyway. I'll post more images later.
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Gary Weinstein May 08, 2018 09:17PM
No chrysocolla. the color coming through the quartz is celedonite, the first mineral to cool in the pocket.
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Kevin Conroy May 08, 2018 10:08PM
The "green" crystals may be quartz on the celedonite.
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Greg Simmons May 08, 2018 10:43PM
OH! interesting. would celedonite be in association with Stilbite and Heulandite then? as opposed to baryte and hemmimorphite?
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Gregg Little May 08, 2018 11:39PM
No, celadonite is a member of the mica group of minerals and commonly forms by lining vesicles early in the crystallization sequenced so it associates or is commonly coated with zeolites, calcite, quartz, etc.



Edited 1 time(s). Last edit at 05/08/2018 11:41PM by Gregg Little.
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Greg Simmons May 10, 2018 03:50AM
Ok. here are some more pix.

This is a larger crystal, I think it's the same stuff as the smaller ones but older and a brownish color.
This one is a cluster of the, are we calling Huelandite(?), crystals are less than 1cm.
This one is the biggest cluster and you can see several of the "rice" like crystals too.

If anyone can think of a specific photos that would assist let me know and I"ll take more.
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Greg Simmons May 10, 2018 02:43PM
So at this point do we have a possible consensus that it is quartz after Celedonite with Stilbite and Huelandite, and likely from India, potentially Maharashta? IF so, what is the best to catalog it as?
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Gregg Little May 12, 2018 06:37AM
Where you say "quartz after celadonite" would infer that quartz is replacing celadonite but the quartz is not replacing but rather it has just grown on top of the celadonite as a coating. The probable heulandite and stilbite is with the quartz. I am still not sure of the crystal in the picture labeled "olderbarite.jpg".
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Alfred L. Ostrander May 14, 2018 02:08PM
I always thought celadonite was an alteration product of the basalt. A little bit different than crystallizing out or first mineral to cool. I know, pedantic picayune.
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Alfred L. Ostrander May 14, 2018 03:07PM
Greg,

Please consider this as a probable sequence of events and minerals formed.

The minerals have formed in a vesicle in basalt. A vesicle is an empty opening often a gas pocket. When filled with minerals it is often called an amygdule.

The basalt walls where then altered and the celadonite is formed.

It appears that after the celadonite has formed a layer of small quartz crystals formed. Linings of small crystals like this are often called a druse, druze, or drusy. All three being used to describe a habit of quartz. Saying quartz after celadonite implies a pseudomorph is present. You should think of sequence and association. Consider thinking of this celadonite followed by quartz. Just look at the layers and see if you can determine what the sequence. Include the basalt matrix as the first step.

Considering the next step, the question of stilbite or hemimorphite can be reasonably settled by considering the environment of formation in that this is an environment far more suitable for stilbite rather than hemimorphite. Stilbite can be white or pink but more importantly is the habit. Stilbite in the probable environment here will most likely show a sheaf like bundle of crystals. The small rice like crystals are also most likely stilbite.

As to baryte, it can be found in this environment but the environment favors heulandite. The overal crystal morphology appears more like heaulandite. If any of the faces of these crystals have a pearly sheen it is most likely heaulandite.

You are correct when you made the step in logic that the celadonite, quartz, stilbite and heualndite are a likely sequence of minerals for the environment.

Identifying minerals and localities from photos can be tricky but some sequences, habits, and matrix lend themselves to reasonable conclusions. This specimen is most likely from the basalt traprock found in the state of Maharashtra in India. I prefere using the traprock term as not all the minerals present are zeolites although it has become common to refer to the specimens from India as zeolites. Traprock comes from an old German term for basalt and the minerals present are all known to be common in this environment. Older literature refered to this as the traprock suite. I like this definition as it starts with the original rock and includes all the minerals present, zeolite or not.

Enjoy your specimen!
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Greg Simmons May 14, 2018 05:34PM
Alfred, et al,
Thanks gentlemen, for your insights. It has been very helpful. Alfred, my original instinct was indeed that the creamy crystal cluster, and the rice like ones were stilbite. Until now I'd never heard of celadonite and so I went to the mineral I know that was most like it, forming a blue-green crust under the quartz, so I figured it was chrysacolla. That then made me question my assumption of the stilbite and sent me on the search for an alternative, hence the thought it might be hemmimporphite.

Now that i've enjoyed the insight from everyone, I have one final question, which relates to cataloging it. What would be appropriate to use as the primary mineral? would it be the first one to form, the celadonite, or the one most prevalent, which I think would be the quartz druze?

Thanks again everyone. I look forward to learning more as I start cataloging my collection.

Greg
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Gary Weinstein May 14, 2018 08:31PM
I usually label such specimens as "Stilbite crystals and Heulandite crystals on Quartz crystals". leave out the matrix as it is not as important to most collectors.
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Greg Simmons May 15, 2018 04:34PM
Great! Thanks Gary.
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Doug Daniels May 16, 2018 01:44AM
I'd label it based on the species you feel is most important. Sometimes that's a judgement call that we all have to make for a particular specimen. Any which way, great specimen!
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Greg Simmons May 16, 2018 04:38PM
Thanks to all. Any pointers on the photography? Since I'm planning to start cataloging my collection I'll be putting together a light box. These pix were just taken outside in the sun. I've heard a lot about focus stacking but never attempted it.

I didn't record f-stop or anything like that, though I think the info is in the camera, but I will going forward. I'm using a 28-135mm lens on a Canon T5i. Most of my collection is cabinet to large cabinet with only a few thumbnails.

Any feed back would be appreciated.
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Hiro Inukai May 16, 2018 10:34PM
Hi Greg,

Even when one's collection is of cabinet+ size specimens, you may find yourself wanting to capture specific small details and features from time to time. For this reason, you should consider investing in a dedicated macro lens for such work. For your camera body, I recommend the recently released Canon EF-S 35mm f/2.8 Macro IS STM. This lens has an integrated LED ring light that facilitates subject illumination for close-up work. With a cheap extension tube, magnification exceeding 1:1 is possible, although the short working distance at the 35mm focal length limits the amount of extension to 25 mm or less.

If you are more serious about macrophotography of mineral specimens, you may wish to consider a lens like the EF 100mm f/2.8L Macro IS, or if you need magnifications as high as 5:1, the MP-E 65mm f/2.8. But the latter should be used with the MT-24EX or MT-26EX-RT flash. But this is a substantial investment, and ironically the large barrel diameter of the MP-E inhibits photography at maximum magnification. For magnifications between 5:1 and 10:1, one should start looking into things like Mitutoyo infinity-corrected microscope objectives. But by then you're firmly in micromount territory and that kind of photography is a whole other discipline.

One should also not forget third-party lenses, such as those from Venus Optics; some can go from infinity focus down to 2:1 without extension.

For non-macro photos of whole cabinet specimens, the attention should be on the aesthetic presentation and illumination. The choice of suitable focal length depends on the desired perspective: this is a point not to be overlooked. Without going into too much detail, I would recommend a longer focal length and photographing the specimen from further away. You should consider arranging a backdrop, made of either fabric or paper, neutral color (black, white, or gray).

Lighting is the most important part of mineral photography. Some specimens are best photographed under diffuse lighting such as from a light box placed as close to the specimen without entering the camera frame. Other specimens are best shot with point light sources. The difference is in the size of specular highlights and the contrast of shiny objects in the scene. Many crystals look dull or flat when photographed under diffuse light. Still other specimens need special lighting--ultraviolet to capture fluorescence; or if translucent, may benefit from being lit from behind to illustrate the internal clarity and structure. There is no single lighting solution that applies to all specimens.

There's so much to explain and share about photography that there's a separate area of the messageboard for it, so maybe it's best for me to stop here. Forgive the gratuitous photo, but here is an example of my photographic work. Chalcopyrite on calcite, Sweetwater Mine, Reynolds County, Missouri. Horizontal field of view approximately 12 mm.


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Greg Simmons May 17, 2018 09:01PM
Wow! Thanks Hiro. That's some great information to digest. I appreciate you taking the time and especially for the information regarding different lighting options based on the mineral type. I hadn't considered that crystals would look flat under diffuse light but it makes complete sense.

Best,
Greg
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