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Author: Subject: Crystal Growing
Sandmeyer
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[*] posted on 22-4-2006 at 17:45


Good work chemoleo, that's really hell of a crystall!
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[*] posted on 23-4-2006 at 10:10


chemoleo's crystals are quite impressive. At first, I didnt notice the coin, once I did, WOW.

Copper (II) Chloride works pretty well for growing crystals too.
I made some CuCl2 once and left it in a pan to dry. I forgot about it for a month and when I came back, it had formed into green and blue (Hydrated I assume) crystals on the sides and bottom of the container.
Had I been trying to make crystals and put a seed in there to start, I probably could have gotton something pretty good.

CuCl2_Crystals.jpg - 63kB
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12AX7
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[*] posted on 23-4-2006 at 10:59


CuCl2 sucks for crystallization, it makes those acicular mats of crystals :rolleyes:

[How come we *still* don't have a rolleyes smiley?]

That's an interesting bed of crystals though :)

I've got a salt that makes large crystals easily, I have no idea what it is, it seperated from my failed urea fermentation experiement. When I grow a big crystal I'll take a picture...

Tim




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[*] posted on 25-4-2006 at 05:22


OK, I've got some CuCl and was going to try crystal growing with it but probably wont bother now - may still try anway.

12AX7 - check out the smilies they have available at http://www.chemicalforums.com/index.php?op=forum

there are some funny ones.
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12AX7
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[*] posted on 27-8-2006 at 11:47


Speaking of CuCl2-- I think I've discovered that a strong HCl solution (enough for a burning odor, probably 10-20%) grows crystals better than impurities having anything to do with it.

Might I hazard a guess that the common ion effect reduces solubility, allowing crystals to organize better?

Tim




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[*] posted on 7-9-2006 at 12:28


What about copper(II) acetate, it is ok for makign large crystals?



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[*] posted on 7-9-2006 at 13:31


Quote:
Originally posted by 12AX7
Speaking of CuCl2-- I think I've discovered that a strong HCl solution (enough for a burning odor, probably 10-20%) grows crystals better than impurities having anything to do with it.

Might I hazard a guess that the common ion effect reduces solubility, allowing crystals to organize better?

Tim

No, CuCl2 actually dissolves better in very concentrated HCl than it water. This is due to complex formation. A yellow/brown complex is formed, most likely CuCl4(2-), but probably also HCuCl4(-) and H2CuCl4. The crystals, obtained by crystallization from HCl contain a lot of acid, and they also have a different color than pure CuCl2.2H2O. The pure salt is cyan/blue, the stuff, obtained from HCl to my experience is much more green with a yellow tinge. Below follows a picture of CuCl2.2H2O.



[Edited on 7-9-06 by woelen]




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12AX7
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[*] posted on 7-9-2006 at 14:09


Ya, about the same as my stuff (see my copper salts page).

The stuff I get is certainly green when moist, but I always attributed that to solution, which is certainly going to stick well (capillary action) given the nature of the hairy crystal blooms.

Well I crystallized some more just today, check it out for yourself.





(Second is sideways and upside-down view of same.)

Most of the liquor has been poured off, which means there's plenty still stuck inside the growth, which has to be broken up and squeezed in filter paper (vacuum would be better!). The liquor is definetly thick deep green, with only a tinge of yellowness. It looks yellower on soaked paper towel, but I would like to think that's due to stuff in the paper oxidizing (copper shouldn't affect cellulose much in that way, though).

Your product may be a bit bluer than mine, lemme see... eh the contents of this jar (now much more than just the little bottle shown on my site) is definetly not as dramatically blue as yours. On opening it smells strongly acidic, not of any particular odor (except the odor that wasn't well cleaned from the jar before I got it). Maybe I'll dry it out a bit more...

Tim

[Edited on 9-7-2006 by 12AX7]




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12AX7
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[*] posted on 13-9-2006 at 17:21


I'm growing (recrystallizing I should say) some ammonium sulfate lately. This is one byproduct of the first urea fermentation thing, that didn't do anything; as the urea hydrolyzed I added sulfuric and hydrochloric acids to neutralize pH.

When I dissolved the stuff in tap water, nothing happened. I filtered the solution and evaporated it down until it started crystallizing. After stirring, causing a hard mat of fine crystals to precipitate, I filtered and redissolved the material. This left a small amount of small transparent acicular crystals, approximately several mm in length and evidently low solubility.

Yep... you know it, calcium strikes again!

Just an FYI, and I suppose the possibility of growing gypsum var. selenite crystals, small ones at least, at home.

(Oh and as for the (NH4)2SO4, I have some blocky, misshapen, clear to milky, colorless crystals on hand, soon to be more.)

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chemoleo
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[*] posted on 11-4-2007 at 15:17
Giant gypsum crystals the size of trees!


Now I just wish I had some of these! Look at the size of the person!




They just recently worked out how such big crystals could form naturally. Check http://www.spiegel.de/wissenschaft/natur/0,1518,476553,00.ht... for the Germans here.

In a nutshell, this is 300 m below ground, found through mining, in a grotto in Mexico, the Chihuahua desert (Naica).
Up to millions of years, 54 deg hot water filled this grotto, depositing CaSO4*2H2O, and the temp must have been extremely stable otherwise the crystals couldnt have grown (i.e. the anhydride ones would have formed instead). The crystals are now in the dry becuase groundwater is pumped away for mining. As soon as the pumps stop, the crystals will start growing again!
For reference, the biggest such crystal made in a lab measures 2 cm in length! If one of these crystals is 10 m long, and say that it takes 1 cm/year for growth (which is likely an overestimate), then they would have been growing at least 10000 years!

Darn I'd love to have one of these in my house!

The original article from the journal 'Geology' is here
http://www.gsajournals.org/perlserv/?request=get-abstract&am...

Quote:

Title: Formation of natural gypsum megacrystals in Naica, Mexico
Abstract:Exploration in the Naica mine (Chihuahua, Mexico) recently unveiled several caves containing giant, faceted, and transparent single crystals of gypsum (CaSO4•2H2O) as long as 11 m. These large crystals form at very low supersaturation. The problem is to explain how proper geochemical conditions can be sustained for a long time without large fluctuations that would trigger substantial nucleation. Fluid inclusion analyses show that the crystals grew from low-salinity solutions at a temperature of ∼54 °C, slightly below the one at which the solubility of anhydrite equals that of gypsum. Sulfur and oxygen isotopic compositions of gypsum crystals are compatible with growth from solutions resulting from dissolution of anhydrite previously precipitated during late hydrothermal mineralization, suggesting that these megacrystals formed by a self-feeding mechanism driven by a solution-mediated, anhydrite-gypsum phase transition. Nucleation kinetics calculations based on laboratory data show that this mechanism can account for the formation of these giant crystals, yet only when operating within the very narrow range of temperature identified by our fluid inclusion study. These singular conditions create a mineral wonderland, a site of scientific interest, and an extraordinary phenomenon worthy of preservation.



[Edited on 11-4-2007 by chemoleo]




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[*] posted on 14-4-2007 at 08:27


I may be getting cynical in my old age but that's the April issue of that journal and I have never seen a cave that well lit. I suspect shotoshop.
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chemoleo
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[*] posted on 14-4-2007 at 09:35


Nono... lol what are you on about?. Obviously they put big lights in there, for the photoshots. You can see certainly crystal faces in the dark spots being bright, indicating a specific light source.



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[*] posted on 14-4-2007 at 22:25


Those are amazing! I bet its closed and no tours though:(. I would love to see them in person.

I can't imagine they wouldent use as much fancy lighting as possible for something like that!




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[*] posted on 16-4-2007 at 10:15


OK, I admit I was being paranoid; there are enough references on the web to thoses mines that I believe them.
On the other hand I have taken photographs in caves and it's difficult. I'm doubly impressed.
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[*] posted on 17-4-2007 at 01:02


here`s some Copper Chloride I made a while back, it looks more like Woelens than the other Green/yellow sorts?

http://myweb.tiscali.co.uk/yt2095/experiments/copchlor1.jpg
http://myweb.tiscali.co.uk/yt2095/experiments/copchlor2.jpg

all I used was Copper Carbonate in HCl (20%).




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[*] posted on 17-4-2007 at 01:21


Quote:
Originally posted by YT2095
here`s some Copper Chloride I made a while back, it looks more like Woelens than the other Green/yellow sorts?


It comes back to having excess HCl or not, which forms the yello-green complex, and having it good and dry, as strong solutions of CuCl2 are brown-green so a thin film of moisture hides the blue colour.
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[*] posted on 17-4-2007 at 01:43


Quote:
Originally posted by Bromine
What about copper(II) acetate, it is ok for makign large crystals?


it`s not bad at all actually, here`s some pics of the copper acetate I made a while back.

http://myweb.tiscali.co.uk/yt2095/experiments/cuac1.jpg
http://myweb.tiscali.co.uk/yt2095/experiments/cuac2.jpg

being such a Dark crystal it`s hard to do them justice in a photo using a cheap cam, but if you notice the odd shiny bit, that`s a crystal face reflecting window light, the crystals are Beautiful up close too.




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[*] posted on 17-4-2007 at 08:33


Izzat kinda like KMnO4 (dark-ass colored), but blue instead?

Tim




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[*] posted on 17-4-2007 at 08:35


I tried to do some before, i got crystals like on your picture. They look nice to me.



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[*] posted on 17-4-2007 at 10:24


Quote:
Originally posted by 12AX7
Izzat kinda like KMnO4 (dark-ass colored), but blue instead?

Tim


naah, these are more a Mega deep Emerald green towards Black.
powdered or scratched they`re Emerald green, whole they`re Black to look at.
and potassium Permanganate when In large crystals would be a good analogy, they too can look almost black when perfect :)




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[*] posted on 19-4-2007 at 16:17


For ease of growing, you can't beat sodium potassium tartrate.

Once, I got a huge bag, cause it was contaminated w/ NH3 and useless for making the ammonia analysis buffer they used it for. I'm just messing around, not serious at all. I poured it in some tap water, mixed it well, poured the saturated sol'n off the excess. Then, I took a bit of that and made a seed crystal, tied a thread around it...etc. I covered the whole thing with cheesecloth, forgot about it.

I go back to check it a few weeks later, and...OH MY GOD! I'd grown a crystal about the size of a golf ball.
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[*] posted on 22-6-2007 at 02:50
Crystal Growing


I found a interesting site last night on crystal growing.

It is http://www.waynesthisandthat.com/crystals.htm

I am trying some of the ones he has listed on there now, I'll post my results.

I have also done some work with rapid/slow cooling of Potassium Nitrate saturated solutions.

Also last night I tried rapid cooling of a saturated salt solution with some neat effects.

Anyone else done any work with this kind of stuff?

-ssdd
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[*] posted on 22-6-2007 at 05:11


Yea - check this out! Particularly chemoleo's copper sulphate!

http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...
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[*] posted on 26-6-2007 at 06:07


Has anyone here grown any crystals of more unusual compounds? I'm really interested in crystal growing and although I haven't mastered it exactly, I'm interested in what other people are doing. Personally, I would do anything for a large, perfectly formed crystal of UO2(NO3)2*nH2O (I'm not sure of the hydration number). I also understand that rare earth sulfates and chlorides make for very good crystal growing compounds.
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[*] posted on 26-6-2007 at 15:30


At work I accidently grew a crystal 1cm x 1cm x 5mm of bromoadamantane. Thats what I get for leaving my waste in a beaker evaporating because I was too lazy to empty the full organic waste bucket:P.

I will post a pic tomorrow, it adopts a form similar to how bismuth crystallizes, but colorless.




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