Sciencemadness Discussion Board - Alum Crystals Thread

Alum Crystals Thread

Chemist_Cup_Noodles - 28-4-2016 at 07:54

So I've just recently learned about what the group of compounds known as the alums are. I've seen the word alum thrown around a lot, most often preceded by potassium and/or aluminum, but never knew exactly what it meant. Thanks to @crystalgrower's neato website I now know exactly what they are! This group of compounds can certainly have a lot of beautiful combinations, so I'm very intrigued.

However, I do have one question about these. For an alum to form correctly, can it be comprised of any cation in a +1 and +3 oxidation state? If it can this opens a world of opportunities. If you can, could it be possible to maybe react a copper (I) sulfate and aluminum sulfate to get a copper (I) alum? I know that copper sulfate exists mostly with copper (II) but isn't copper (I) sulfate theoretically possible?

A few common +3 oxidation state cations I think would make some neat crystals are Co⁺³, Cr⁺³, Al⁺³, and Fe⁺³. Some +1 oxidation state cations I think might produce interesting results are NH₄ ⁺¹, K⁺¹, Na⁺¹, and maybe even Cu⁺¹. I know that the cuprous form of copper isn't super common, but it's not very hard to get it to the +1 state and I've seen it done several times on SciMad.
I have some ideas for some different combinations I want to try though. I'll list them: CoK, CrCu, FeNH₄, CoNH₄, CrNH₄, or AlCu.

No idea if they'll work or not, but oh what the hell, why not.
If you have any experience with these, pictures, or perhaps produced rather interesting crystals, please share!

I will note though, I usually do a lot of reading and fact checking before making a post, reply, or topic but for this one I'm kind of throwing a healthy amount of conjecture at the wall.

DraconicAcid - 28-4-2016 at 08:13

Cu(I) is only stable in the form of insoluble compounds- you aren't going to get an alum with it.

blogfast25 - 28-4-2016 at 08:43

Bear in mind also that the solubility of alums tends to decrease with increasing size of the M⁺ ion. For that reason many Na⁺/Li⁺ alums cannot be crystallised, because they are too soluble.

Other 'exotic' alums include Rb/Mn³⁺ and Cs/Ti³⁺.

Never heard of a Co³⁺ based alum. Co(+3) is a powerful oxidiser (oxidises chloride to chlorine), so may be not stable enough.

Chemist_Cup_Noodles - 28-4-2016 at 08:56

Quote: Originally posted by DraconicAcid

Cu(I) is only stable in the form of insoluble compounds- you aren't going to get an alum with it.

Damn, I was afraid it would be too unstable. If it weren't I'm sure it would have produced some beautiful crystals. Oh well, would a potassium cobalt (III) alum still be possible, or ammonium cobalt (III) alum? The +3 state of cobalt seems to be more stable than the +1 state of copper, but the +2 state of cobalt still seems much more optimal than the +3. I haven't seen where the +3 state can form crystals though so I'm losing hope for that. It seems like it forms a lot of different Werner complexes though, so that's interesting.

DraconicAcid - 28-4-2016 at 09:24

http://pubs.acs.org/doi/abs/10.1021/ed079p958

Yes, you can make cobalt(III) alums. You just need a really big cation.

ETA: Why do you think Cu(I) would give beautiful crystals? Cu(I) is a d10 system and will be colourless in the absence of charge-transfer or Cu(II) impurities. That's why pure CuCl, CuBr, CuI, etc are all white powders.

[Edited on 28-4-2016 by DraconicAcid]

crystal grower - 28-4-2016 at 09:27

Maybe that's a right time to attempt making some unconvetional alums

.
I will let you know if I succesfully make some pretty alum

Chemist_Cup_Noodles - 28-4-2016 at 10:41

Quote: Originally posted by DraconicAcid

http://pubs.acs.org/doi/abs/10.1021/ed079p958

Yes, you can make cobalt(III) alums. You just need a really big cation.

ETA: Why do you think Cu(I) would give beautiful crystals? Cu(I) is a d10 system and will be colourless in the absence of charge-transfer or Cu(II) impurities. That's why pure CuCl, CuBr, CuI, etc are all white powders.

[Edited on 28-4-2016 by DraconicAcid]

Oh, I'm glad you've found an article on cobalt alums! Too bad you have to pay to see it though. I don't have an ACS membership yet so I can't even see the reduced price. But from the abstract it seems that a cobalt ammonium alum is possible, and I also found it on another neat site. This site also lists a that a potassium cobalt alum has been made before, by someone named "Marshall". So I know it showed a cesium cobalt alum in the article abstract, but now I don't know if a cation that big is really necessary if it's evidently worked with potassium (although it was only a sourceless blurb, so I'm a little skeptical actually).

But about Cu(I), I really didn't think or know that it was colorless. I just knew that Cu (II) makes a lot of great blues and greens, and that there was cuprous sulfite in Chevreul's salt that lent to the deep red color, but I suppose that is also due to the fact that cupric sulfite is present also. To be honest I've never worked with copper in it's first oxidation state. And like I said in my post, this is mostly me just throwing around conjecture, so thank you for correcting me (I hate how sarcastic that sounds in my head but it's sincere so oh well).

On another note, I searched up the CsTi alum, and apparently it has paramagnetic properties which is pretty cool. I saw a thread elsewhere on SM where a guy tried but failed at making a titanium alum, so I didn't think it would work. And could manganese alums be something else to look into? I didn't initially think they would work because I did remember how strong of an oxidizer Mn³⁺ was, and it's rather uncommon to see it in that state. But I was reading the page in Encyclopedia Britannica on it, and it had manganese listed so maybe it does work.

DraconicAcid - 28-4-2016 at 11:52

Yes, you can make an alum with Mn(III).

https://books.google.ca/books?id=xnsAAAAAMAAJ&pg=PA621&a...

I have a prep for manganese(III) sulphate at work- I'll give you the reference later.

ETA: Vogel's Quantitative Inorganic Analysis sez...

Preparation and Standardization of manganic sulphate solution.

To prepare a c. 0.07 N solution...

To 50 mL of a solution of A. R. manganous sulphate (15.1 g in 1 L of 6N-sulphuric acid) add 3 mL of conc. sulphuric acid with water-cooling; then add 12 mL of 0.5N potassium permanganate solution, 2 mL at a time, at intervals of about three minutes. After 8 mL and again after 12 mL of the permanganate solution have been added, cautiously introduce a further 2 mL of conc. sulphuric acid. Store the solution for 4 hours before use.

Note that a 0.5N solution of potassium permanganate corresponds to a 0.1 mol/L solution, or about 16 g per litre.

[Edited on 28-4-2016 by DraconicAcid]

blogfast25 - 28-4-2016 at 11:53

Quote: Originally posted by Chemist_Cup_Noodles

I saw a thread elsewhere on SM where a guy tried but failed at making a titanium alum, so I didn't think it would work. And could manganese alums be something else to look into? I didn't initially think they would work because I did remember how strong of an oxidizer Mn³⁺ was, and it's rather uncommon to see it in that state. But I was reading the page in Encyclopedia Britannica on it, and it had manganese listed so maybe it does work.

That 'guy' was me. It would have worked had I tried the Cs/Ti alumn. The K/Ti didn't work and the NH₄/Ti was a bit inconclusive. But forget about making nice, big crystals from these: that would be much harder to do.

Despite Mn(+3) being a powerful oxidiser, reports on Rb/Cs Mn³⁺ alums can be found.

Chemist_Cup_Noodles - 28-4-2016 at 15:15

I think I'm going to attempt to make ammonium iron (III) sulfate first. It doesn't seem too awful to make, all I need to do is first make iron (II) sulfate with iron + excess sulfuric acid, then add nitric acid that I just made to that to oxide it to iron (III) sulfate Fe₃(SO₄)₂. Making ammonium sulfate should be straightforward enough. Then I'll just stoichiometrically combine the two, and crystallize for the alum. Shouldn't be too bad.

But does anyone have any ideas on how to test for iron (II) vs iron (III)?

DraconicAcid - 28-4-2016 at 16:19

Quote: Originally posted by Chemist_Cup_Noodles

I think I'm going to attempt to make ammonium iron (III) sulfate first. It doesn't seem too awful to make, all I need to do is first make iron (II) sulfate with iron + excess sulfuric acid, then add nitric acid that I just made to that to oxide it to iron (III) sulfate Fe₃(SO₄)₂. Making ammonium sulfate should be straightforward enough. Then I'll just stoichiometrically combine the two, and crystallize for the alum. Shouldn't be too bad.

But does anyone have any ideas on how to test for iron (II) vs iron (III)?

The easiest way to make sure your iron is iron(III) is to precipitate it as the hydroxide and leave the suspension exposed to air for a while. Then you can dissolve it in sulphuric acid.

blogfast25 - 28-4-2016 at 17:03

Quote: Originally posted by DraconicAcid

The easiest way to make sure your iron is iron(III) is to precipitate it as the hydroxide and leave the suspension exposed to air for a while. Then you can dissolve it in sulphuric acid.

That's a lot slower than you might think. It also requires constant stirring of the slurry.

There's a preparatory thread on FAA:

http://www.sciencemadness.org/talk/viewthread.php?tid=5650#p...

Cucurbit - 30-4-2016 at 12:08

Quote: Originally posted by Chemist_Cup_Noodles

If you have any experience with these, pictures, or perhaps produced rather interesting crystals, please share!

Here's a crystal of 'ordinary' KAl(SO4)2.12H2O that started as a seed perhaps a year ago... in the meantime it has grown a few more mm

The other alum I've grown crystals from is chrome alum, and this can be mixed with aluminium alum in all proportions, just like a dye.

Those more exotic alums are very interesting, especially cobalt! I have some cobalt(II)chloride which I'll have to convert to the sulphate first.

crystal grower - 30-4-2016 at 12:24

@cucurbit
Your alums are absolutely gorgeous!
Looking forward to cobalt alum

Cucurbit - 30-4-2016 at 13:25

Thanks Crystal Grower! Same specimen as in your nice thread in 'miscellaneous'.
I now have 4 big ones still growing, it's like having a pet or a plant that requires a bit of maintenance but nothing too demanding

The cobalt variety will take some time, as usual with crystals... but I'm very curious about the color. Chrome alum is fascinating: in cold daylight it's violet, but in candle light it's blood red, like a ruby! Who knows what cobalt is going to do. But they will never be as big as my current Big Four!

The Volatile Chemist - 30-4-2016 at 14:53

I wish I'd bookmarked some of the double-salts I'd ran into recently - I assume you don't mind talking about double salts in general because they, being the broader type of solid which includes alums, sometimes have the same ease of crystal-making. I could've swore I saw a magnesium-something double salt with chloride or sulfate which made big crystals. It was also a kind of mineral...

Ah, Magnesium Potassium Sulfate (cite). Also, magnesium potassium chloride and zinc ammonium chloride, both with 1:1 of the two cations. I haven't tried any of these, though. And ferrous and Ferric ammonium sulfates are cool, I own small samples of both. Very pretty.

Chemist_Cup_Noodles - 10-5-2016 at 14:15

Quote: Originally posted by The Volatile Chemist

I wish I'd bookmarked some of the double-salts I'd ran into recently - I assume you don't mind talking about double salts in general because they, being the broader type of solid which includes alums, sometimes have the same ease of crystal-making. I could've swore I saw a magnesium-something double salt with chloride or sulfate which made big crystals. It was also a kind of mineral...

Ah, Magnesium Potassium Sulfate (cite). Also, magnesium potassium chloride and zinc ammonium chloride, both with 1:1 of the two cations. I haven't tried any of these, though. And ferrous and Ferric ammonium sulfates are cool, I own small samples of both. Very pretty.

Hm, another thread on this board where someone wondered if a copper and ferrous sulfate double salt got me searching around. While I knew that is was not possible, my searching around lead me to a wikipedia page on Tutton's salts which seem fairly similar to the alums. The page also has a quite wonderful table of a variety of the salts with plenty of sources. Many of the exotic salts that seem a little out of reach of the average amateur chemist though. The magnesium potassium sulfate you've cited seems to actually occur as a natural mineral too, neato.

Cucurbit - 17-5-2016 at 13:13

Thanks for that link about Tutton's salts, very useful!

I knew about copper ammonium sulphate because of an old book, my 'bible' when I was a kid, 70's... "Scheikunde thuis" by H.L. Heys. My mom threw it away after an explosion in the garage, but the chapter about crystal growing is etched into my brain!

Just made a bit of cobalt sulfate solution (from CoCl2.6H2O and excess Na2CO3, dissolve the carbonate in dilute sulfuric acid)... the beautiful red filtrate is now evaporating.
Next step: combine with potassium sulfate to get the double salt.

Just discovered a video about growing crystals of cobalt(II) ammonium sulphate - never mind the delicious heavy accent

https://youtu.be/nsL_EYIEoG4

The Volatile Chemist - 17-5-2016 at 15:25

Quite the interesting double salt, seemingly vaguely analogous to the Chromium(III) Potassium Sulfate double salt with regards to its properties and coloration.

Neme - 28-5-2016 at 09:34

Hello everyone,
I've got problem with my potassium aluminium alum growing I need help with. My solution is always getting after few days some white floating weird stuff at surface. I think it's mold. I tried warming the solution and filtering it afterwards and with no change. I also tried UV-B light and also nothing.

My idea is to add little bit of sulfuric acid, but I'm little bit scared of interrupting the crystalization.
I would really appreciate help.

blogfast25 - 28-5-2016 at 11:27

A little H₂SO₄ is very unlikely to disrupt crystallisation but likely to disrupt bacterial growth.

crystal grower - 28-5-2016 at 12:13

Sulfuric acid present in the solution often cause crystallization of lower ,hydrate than one which would crystallize from normal water solution.
But I don't know exactly how it would affect the crystallization of KAl(SO4)2.

Cucurbit - 28-5-2016 at 14:10

I don't think it's mold or bacteria, they should have nothing to feed on in the solution. More likely it's aluminium hydroxide hydrate gel, due to hydrolysis.
I had some of these flakes in my solution but it didn't seem to harm the crystals much. Sudden temperature rises are more disastrous

To be sure: a few drops of sulfuric acid should help acidify the solution a bit - not too much. And regular filtering, once or twice a week!

Neme - 29-5-2016 at 00:15

Okey, thanks for ideas, I'm gonna try little bit of sulfuric acid.

The Volatile Chemist - 3-6-2016 at 12:30

Quote: Originally posted by Cucurbit

I don't think it's mold or bacteria, they should have nothing to feed on in the solution. More likely it's aluminium hydroxide hydrate gel, due to hydrolysis.
I had some of these flakes in my solution but it didn't seem to harm the crystals much. Sudden temperature rises are more disastrous

To be sure: a few drops of sulfuric acid should help acidify the solution a bit - not too much. And regular filtering, once or twice a week!

Mold can grow in a lot of stuff, and can get sufficient resources from dust, depending upon its location. If you don't add too much H₂SO₄, then the lesser hydrate, I wouldn't think, would crystallize out. You could always do a prep run.

Neme - 4-6-2016 at 05:15

Well I'm sure it's some sort of organic varmint. I don't have good photo of it, but I'm still adding a link. https://ctrlv.cz/xQBo

Cucurbit - 6-6-2016 at 20:22

It looks like little people are swimming around. Just filter them

[Edited on 7-6-2016 by Cucurbit]

Cloudy possible organics in Alum crystal growth

Dwarvensilver - 8-6-2016 at 13:41

Greets,
I have also run into this floating material, filtering helps but it comes back.
I would appreciate info as to whether H2SO4 helped or not, although It does not seem to have affected crystal growth but hard to tell with the imperfections in the crystal.
Cheers,

Dwarvensilver

Neme - 14-6-2016 at 10:25

Well I did not probably add enough to stop that varmint. I'll add some more then post results again.

Btw: I attach few photos of mine chrom alum crystal.

Cucurbit - 14-6-2016 at 10:50

Wow!! Those crystals are magnificent!

crystal grower - 14-6-2016 at 11:18

Awesome crystal.

Neme - 14-6-2016 at 11:44

Thank you, mine best so far.
Age: 3 months and one week.

Cucurbit - 14-6-2016 at 13:27

Heh, obviously it's only one specimen from different angles.

Three months sounds very reasonable for that size and quality. Keep it growing, in another three months it can double its mass!

By the way, very nice growing conditions here lately (Holland) and the rest of the week, very constant temperature. Nice weather for crystal growers. My two big babies are gaining more millimeters and the new layers are perfectly clear

[Edited on 14-6-2016 by Cucurbit]

Dwarvensilver - 15-6-2016 at 13:25

Greets all,

I am so Glad I signed up here the information is just Bloody awesome!, Thank you everybody for your inputs.

I have access to Ammonium Sulfate, and Ferric Sulfate and I want to make some ferric alum to grow crystals. the recipes here will be of immense help.
I have three different bags of the ferric sulfate, one is quite coarse rough looking multiple size tan beads, one is much smaller beads and much more uniform in size and lighter more yellow color. I believe these are much the same. the last one is marked Ferric sulfate Hydrate and is a fine yellow powder. Any feedback as to which to use or just info on the Hydrated one, cause I thought ferric could not be a hydrate because of decomposition.??

Neme - 22-6-2016 at 10:42

So far is mine solution clear and without any varmint in it. I had to add lil' bit more drops to the solution.

Varmints in Alum crystal Liquor

Dwarvensilver - 23-6-2016 at 10:53

Great to hear Neme
I filtered mine again but the stuff floating around came back quicker.
I will have to add some H2SO4 to see if it will help.
Attached is a couple of pics of current crystals that I am growing.
Red one is Potassium ferricyanide
Green is ferrous sulphate
Brown is Potassium sulphate
All are works in progress

[Edited on 23-6-2016 by Dwarvensilver]

The Volatile Chemist - 23-6-2016 at 11:29

Uh, red potassium ferrocyanide? Perhaps you mean ferricyanide? Or does the solution oxidize in air to ferricyanide? Because so far as I can tell, potassium ferrocyanide should be orangish-yellow, not crimson. No offense to the poster, just curious.

Ferricyanide

Dwarvensilver - 23-6-2016 at 13:11

No Offense taken, and you are perfectly right the red one is Ferricyanide not Ferro.

My pardon for the Error and thanks for pointing that out.

Cheers,

Cucurbit - 23-6-2016 at 13:21

Impressive crystals Dwarvensilver, especially the ferricyanide is very beautiful!

Keep them growing and please keep posting updates

Chemist_Cup_Noodles - 23-6-2016 at 13:22

Quote: Originally posted by Dwarvensilver

Greets all,

I am so Glad I signed up here the information is just Bloody awesome!, Thank you everybody for your inputs.

I have access to Ammonium Sulfate, and Ferric Sulfate and I want to make some ferric alum to grow crystals. the recipes here will be of immense help.
I have three different bags of the ferric sulfate, one is quite coarse rough looking multiple size tan beads, one is much smaller beads and much more uniform in size and lighter more yellow color. I believe these are much the same. the last one is marked Ferric sulfate Hydrate and is a fine yellow powder. Any feedback as to which to use or just info on the Hydrated one, cause I thought ferric could not be a hydrate because of decomposition.??

This site certainly is awesome, and I'm glad you're here too! But I see that you are interested in growing some ferric alums, I've actually been working on making some too for an article on a website run by two other people here on scimad. The one I've been working on producing is Iron (III) potassium alum. As to your question about the hydrate, I was reading the wikipedia article on the salt, and where it discusses various minerals of the salt it mentions that there are hydrated forms, albeit quite rare. But for my production of Iron (III) potassium alum, since I lacked any ferrous or ferric sulfate, I decided to start from the ground up while making it. My procedure was fairly standard for making alums, just tweaked a bit to make up for my lack of the iron sulfates. Basically, I mix KNO₃ and excess sulfuric acid in a flask to produce potassium sulfate and nitric acid with plenty of acid left over in order to make a highly oxidative mixture. Then, I dissolve iron in slightly excess heated sulfuric acid to form the ferrous sulfate, and then add that into the flask to get oxidized into ferric sulfate. It's kind of scary though because it evolves a ton of NO₂ but I lack access to strong hydrogen peroxide, so I have to make do. I have yet to try to get some crystals from this, but when I do I will surely post them!

Dwarvensilver - 23-6-2016 at 13:55

Thanks Cucurbit, I will,
Below is a pic of my book shelf at work lol
I work in Research so I have access to literally hundreds of chemicals to try and crystalize.
the big Copper sulphate ones against the wall is what got me started.

Cheers,

Bookshelf.JPG - 126kB

Ferric potassium sulphate

Dwarvensilver - 23-6-2016 at 19:36

Wow Chemist_cup_
I am limited as to how much actual chemistry I can do.
I would so love to do the process you outline. Let me know how it goes!

You have given me the bug tho, I have some cobalt film and powder I think I will try to get some cobalt chloride going with a little HCl.

[Edited on 24-6-2016 by Dwarvensilver]

Neme - 23-6-2016 at 21:00

Well I guess I have to post another few photos of mine

1st photo: potassium ferricyanide little crystals growing
2st photo: weird effect of potassium ferrocyanide - capillary elevation?
3rd photo: potassium aluminium alum experiment with food dye
4th photo: blue vitriol

001.jpg - 1.9MB

Dwarvensilver - 25-6-2016 at 13:55

Nice work Neme. Those look great!!!
I am working on growing Boric acid, (so far it is only making very thin platelets)
Cobalt sulphate, Lead Nitrate (white octocubic shape), I will post pics when they get bigger,
Cheers,

crystal grower - 26-6-2016 at 01:16

Quote: Originally posted by Dwarvensilver

Nice work Neme. Those look great!!!
I am working on growing Boric acid, (so far it is only making very thin platelets)
Cobalt sulphate, Lead Nitrate (white octocubic shape), I will post pics when they get bigger,
Cheers,

Hello Dwarvensilver, I have also grown boric acid crystals, they were in form of platelets too, but I also noticed some small prismatic crystals, although Im not sure what conditions are needed to form these prisms, I think they are formed at temperatures ~70 degrees of celsius.

The Volatile Chemist - 26-6-2016 at 19:07

Really pretty stuff. And I'd noticed the same effect in some ferrocyanide solution too. And I think I've finally hit on what I'd like to focus on in my experiments. Indicators and crystals. 'Pulvers' - I'm bad at. Ochem - bad at. Inorganic chem - can hardly ever get my HCl to do what it's supposed to because it has so darned much Fe(II) in it. So making double salts might just be it for me, we'll see...

Anyone know of any lead alums?

Neme - 26-6-2016 at 20:34

Since lead is usually occuring as II or IV and alums have one I and III, I doubt there is an alum of it.
You still can look for lead tutton's salts but I don't know if they exist either.

The Volatile Chemist - 27-6-2016 at 09:02

Quote: Originally posted by Neme

Since lead is usually occuring as II or IV and alums have one I and III, I doubt there is an alum of it.
You still can look for lead Tutton's salts but I don't know if they exist either.

Oh, geesh, I'm bad at chemistry in the late night. I was referring to double salts in general. A lead(IV) double salt would be interesting, as it might be usefully stable. But I might look around for a lead-something nitrate double salt.

Dwarvensilver - 28-6-2016 at 09:47

I looked through A list of Tutton's salts But no Lead listed in it.
(The Volatile Chemist) I am currently growing a Lead nitrate crystal, What do you think would be good candidates to react with Lead nitrate to make a double salt?

Cheers,
Dwarven

crystal grower - 28-6-2016 at 10:03

Wouldn't it be better to discuss about these salts (ferricyanide, lead nitrate,etc.) In this thread ?: https://www.sciencemadness.org/whisper/viewthread.php?tid=64...
I Don't want to offend anyone, I just want to keep this thread on topic.

Neme - 28-6-2016 at 10:45

Sorry for offtopic

to the topic I attach some photos of mine alums

Edit: photos are now smaller

[Edited on 29-6-2016 by Neme]

006.jpg - 159kB

The Volatile Chemist - 28-6-2016 at 12:39

Good point.

An those pictures are nice, but enormous..you might want to find a better way to attach, reduce, or embed them...

Dwarvensilver - 29-6-2016 at 09:40

Thanks crystal grower,
A Pox upon me for being a lout Sir, you are totally right, this is an Alum thread and should be kept so.
Thanks for the link
Cheers,
Dwarvensilver

crystal grower - 30-6-2016 at 06:09

Quote: Originally posted by Dwarvensilver

Thanks crystal grower,
A Pox upon me for being a lout Sir, you are totally right, this is an Alum thread and should be kept so.
Thanks for the link
Cheers,
Dwarvensilver

I'm glad it helped

.
I'm looking forward to every crystal growing projects on this forum

.

[Edited on 30-6-2016 by crystal grower]

Cucurbit - 8-7-2016 at 14:52

Small update on my no.2 alum crystal, it's slowly but steadily becoming no.1 :cool:

Its base has reached edges of 5 cm (2") and I have small hands like Donald Trump's, so the crystal looks extra big

@Neme: Nice work on the crystals, keep going. The chrome alum shows some damage but it can grow back!

alum_in_hand4_small.jpg - 78kB

[Edited on 8-7-2016 by Cucurbit]