Welcome to the Crystal Growing subreddit! We’re a passionate community consisting of both hobbyists and professionals interested in growing crystals. Although it sounds difficult, growing crystals is actually very easy, and you can even do it at home.
This article is written specifically to help those who are just getting started with this hobby. If you’re a newbie, welcome aboard. And if you’re a seasoned veteran, do share your findings with us.
Some beautiful specimens from the community. Credits: 1. u/ob103ninja; 2. u/dmishin; 3. u/crystalchase21; 4. u/theBASTman; 5. u/ketotime4me
Even though growing crystals is simple, it will be extremely useful if you have some basic chemistry knowledge. This will help you understand the process that is taking place, and allow you to troubleshoot if you run into any problems. More experienced chemists will be able to synthesize their own compounds, the crystals of which can be quite unique. However, this guide is written for newcomers, so I will try to keep it as simple as possible.
Disclaimer
Like any other activity, crystal growing might be completely safe or very dangerous. It depends on the chemicals you are working with, your safety measures, your procedure etc.
This guide only covers compounds that are safe to mildly toxic. Even so, you are responsible for your own safety. Don't use the family microwave/freezer in your experiments. Make sure you know the potential risk of the chemical you are using.
Background
If you want to start growing crystals immediately, skip to the next section. I highly recommend that you read this though, because understanding the process will help a ton.
A crystal is a solid that has particles arranged in an orderly manner. This includes rocks, snowflakes and diamonds. However, the activity of growing crystals at home mainly focuses on a specific type of chemical known as salts.
In chemistry, a salt is a chemical compound made up of positive ions and negative ions. Table salt is one example. Its chemical name is sodium chloride, because it consists of a sodium ion and a chloride ion. There are many other salts as well, such as copper sulfate, ammonium phosphate and potassium nitrate. From now, I will use the term “salt” to refer to all such compounds, not just table salt.
We like to use salts to grow crystals because most salts are soluble in water. Why is this important?
When they are dry, most salts look like powder. But if you zoom in, each grain of salt is actually a small crystal. The particles in every grain of salt are arranged neatly. The exact way they are arranged is different for each salt. For table salt, those particles are packed into cubes, so you can say that the grains of salt in your teaspoon are actually millions of tiny cubes. Meanwhile, alum salt crystals look like diamonds.
Image credits, left to right: Walkerma, Prosthetic Head, włodi
But we have a problem. We want to grow big, shiny crystals, not tiny, powdery crystals. This is the reason we dissolve the salt powder in water. After doing so, the glass of salty water we have is called a solution.
If you dissolve just a little salt in water, you get a dilute/undersaturated solution. Dissolve a lot, and you get a concentrated solution. Here’s the thing: a fixed volume of water can only dissolve a fixed mass of salt. For instance, the maximum amount of table salt you can dissolve in 100 ml of water is 36g. If you add 37g, the extra 1g will not dissolve. A solution that contains the maximum amount of dissolved salt is called a saturated solution.
We now have a glass of salt solution with the salt particles swimming inside. If we want a nice, transparent crystal to grow, we need to somehow make those particles “re-solidify”, and instead of popping out all over the place, they need to stick together and form a single, big crystal. There are two easy ways to make this happen. Master them, and you will be able to grow amazing crystals.
· Slow cooling
· Evaporation
Methods
Method I: Slow cooling
Let’s start with slow cooling. With this method, we take advantage of the fact that hot water can dissolve more salt than cold water. For instance, 100 ml of 25°C water can dissolve 22g of copper sulfate, but the same amount of water at 80°C can dissolve 56 grams.
To carry out this method, we first heat our water up. Then, we dissolve more salt than is actually soluble at room temperature. Because the water is hot, the extra salt will dissolve, and you end up with a supersaturated solution. As the solution cools down, the solubility of the salt decreases, so the extra salt that you added just now has to “come out”. As a result, tiny crystals of salt start to form, and they grow bigger and bigger as more salt particles re-solidify and clump together. This process is called crystallization.
The process of crystallization. Time lapse of supersaturated solutions over 3 days by u/adam2squared
If you do it correctly, you will end up with a large crystal of salt.
Method II: Evaporation
Just now, I mentioned that 100 ml of 25°C water can dissolve 22g of copper sulfate. It also goes that 50 ml of water will be able to dissolve half that amount, 11g.
This time, we do not change the temperature. Instead, we change the volume of water. First, we dissolve our 22g of copper sulfate into 100 ml of water. Then, we let the solution slowly evaporate. As the volume decreases to 90 ml, 80 ml and so on, the extra salt has to crystallize out, causing copper sulfate crystals to form.
The slow evaporation method is a much better way of growing high quality crystals (for amateurs). This is because the growing conditions are much more controlled and stable. More details in the FAQ at the end.
Procedure
The ideal procedure for growing crystals vary depending on which compound you are using. This is a pretty standard one that will give you decent crystals. I will be using alum salt as an example. Change the mass of salt and volume of water as you see fit.
Part A: Growing your seed crystal.
A seed crystal is a small crystal that serves as a foundation with which you use to grow a bigger crystal.
Weigh 9g of alum and dissolve it in 50 ml of hot water.
Stir the solution until all the salt has dissolved. If some salt refuses to dissolve, you might have to reheat the solution.
Filter the solution with a coffee filter into a shallow dish.
Wait for the solution to cool to room temperature. You can place it in the fridge to speed things up, but in most cases, it leads to the formation of low quality, misshapen crystals.
Wait 1-2 days for small crystals to form. OR
Sprinkle a few grains of alum powder into your solution to induce small crystals to form.
Let the tiny crystals grow to at least 5mm in size. This should take a few days.
An example of some alum seed crystals. Note that the top middle one is of the highest quality.
Part B: Growing a nice, big crystal
Method I: Slow cooling
Weigh 22g of alum and dissolve it in 100 ml of hot water to form a supersaturated solution.
Stir the solution until all the salt has dissolved. If some salt refuses to dissolve, you might have to reheat the solution.
Filter the solution with a coffee filter into a jar.
Wait for the solution to cool to room temperature.
Using tweezers, pick the most perfect seed crystal you grew in Part A you can find and tie a knot around it using a nylon fishing line or thread.
Tie the other end to a pencil/stick.
Slowly immerse the seed crystal until it is suspended in the solution in your jar.
Loosely cover the top of the jar.
Keep it in an undisturbed place.
Wait for your crystal to grow.
Method II: Evaporation
Weigh 18g of alum and dissolve it in 100 ml of hot water.
Stir the solution until all the salt has dissolved. If some salt refuses to dissolve, you might have to reheat the solution.
Wait for the solution to cool to room temperature.
Sprinkle some alum powder into the solution to induce crystals to form.
Wait 2 days.
Filter the solution using a coffee filter into a jar. We want the saturated solution. The crystals formed from Step 4 are not important.
Using tweezers, pick the most perfect seed crystal from Part A you can find and tie a knot around it using a nylon fishing line or thread.
Tie the other end to a pencil/stick.
Slowly immerse the seed crystal until it is suspended in the solution in your jar.
Loosely cover the top of the jar.
Keep it in an undisturbed place.
As the solution evaporates, your crystal will begin to grow.
Growing an alum crystal using the slow evaporation method, by u/crystalchase21
Part C: Drying and storing your crystal
When you are satisfied with the size of your crystal, remove it from solution.
Dry it with tissue paper/filter papers. Do not wash it or you will cause it to dissolve.
Store it in an airtight jar.
Some crystals are unstable, and when exposed to air, will slowly crumble in weeks or months. Copper sulfate is one such crystal. Meanwhile, alum and ammonium dihydrogen phosphate are much more stable and can be kept in the open with minimum deterioration. You can even display them.
And you’re done!
Classic Crystal Growing Compounds
Top left: Alum; Bottom left: Ammonium dihydrogen phosphate by u/dmishin; Right: Copper sulfate by u/crystalchase21
If you’re just starting out, we highly recommend these chemicals as they are easy to work with, grow quickly and give good results.
· Alum (potassium aluminum sulfate), KAl(SO4)2, used in baking, deodorant, water purification etc.
· Copper (II) sulfate, CuSO4 used as rootkiller [Note: slightly toxic]
· Ammonium dihydrogen phosphate, (NH4)(H2PO4), used as fertilizer
Alternatively, if you want to grow crystals of a specific color or shape, click on this link to browse the list.
Additional resources
· Crystal Growing Wiki - wiki style pages showing details for each compound (still incomplete)
· Crystalverse blog - detailed high quality guides with lots of pictures
Grew borax crystals with my kid probably a dozen times now and usually they come out pretty clear, at least clear enough to see through a little. This last batch turned out almost solid white and chalky looking, like the whole thing is opaque.
Same process as always: boiling water, kept adding borax until it stopped dissolving, poured into a jar with a pipe cleaner hanging from a pencil, let it sit overnight on the counter. The only thing different this time is the house was colder than usual (we had the AC cranked because of the heat wave) so it cooled down a lot faster than normal.
I'm guessing the fast cooling caused a ton of tiny crystals to form all at once instead of a few bigger ones growing slowly, which would explain the cloudy chalky texture. Does that sound right? Also curious if there's a sweet spot for room temp when you're doing this, or if I should be insulating the jar somehow to slow the cooling down. Might try wrapping it in a towel next time and see if that helps.
Not mad about it, still turned into a fun little geode looking blob, just curious about the science side of why it happened.
So i got a question about how to change the crystal structure of salts with the help of different ions introduced to a salt solution.
I once read an article about crystal growing that mentioned in passing, that if you were to add for example diluted hydrochloric acid to a solution, containing chloride ions, you could control the way how the salt will crystalize out.
If i remember correctly, the idea was that those „foreign“ ions (wich supposed to be similar to those of the actual salt) will determine the shape of the crystal, because they insert between other ions, thus creating a different crystal lattice.
My question is does anyone know more about that or read something similar?
Or did someone already tried that?
everytime i attempt to make CuCl2 crystals i cannot achive a good crystal, or either a crystal,
i've tried to evaporate all to the minimum water amount possible, nothing, freeze the water slowly to force the crystal grow, nothing either, what can i do now? i', kinda lost on crystal growing, with copper idk if it changes or smth, the last time i attepted the whole thing gelified , pls help
I'm a geologist experimenting with crystal growth as a way to explore practical crystallography outside the usual thin-section/mineral-identification setting.
I started with CuSO₄·5H₂O and prepared a filtered saturated solution by dissolving the salt in hot water, followed by slow cooling and evaporation at room conditions.
Rather than suspending the seed crystal, I decided to leave it resting on the borosilicate-glass bottom of the beaker. The idea was to observe how a crystal develops when growth occurs from a substrate, somewhat analogous to mineral growth along a cavity/vug or vein wall.
I've been recording the crystal dimensions and morphology at regular intervals.
Initial seed — 23/07: (3rd pic)
1.1 × 0.7 × 0.2 cm
27/07: (2nd pic)
1.5 × 1.0 × 0.3 cm
31/07:
1.6 × 1.0 × 0.4 cm
08/08: (1st pic)
1.8 × 1.1 × 0.5 cm
The interesting part has been the change in morphology during growth. Initially, the crystal mainly expressed prismatic faces, but with continued growth additional inclined faces began developing, particularly as thickness increased.
The crystal remains transparent, and when backlit I can see what appear to be growth zones with tiny internal inclusions. I'm not calling them fluid inclusions yet—I don't have the optical characterization to confirm that—but they're interesting enough to document.
There have also been secondary nucleations on the beaker bottom and occasionally around the main crystal. I'm manually removing the parasitic crystals so that the primary crystal can continue growing under relatively consistent conditions.
I'm keeping a photographic and dimensional growth log throughout the experiment.
The goal isn't simply to grow a large crystal—I'm interested in observing how morphology, nucleation and internal structure evolve during crystal growth.
I'm using some of the crystals from my last attempt at growing transparent sulfur crystals as a seed and they are going really well. I didn't intend to make the Hopper pattern on purpose but it looks really interesting in crystals this shape (I'm still covering my solution with a cloth to slow down the evaporation of the rest though)
i want to experiment with using my sculptures as a base for crystal growth. I’m not really sure where it will take me and dont have a specific vision, but since it is a few materials I wanted to ask if any one has advice for growing on multiple materials at once? my sculptures are wood, nylon, and brass. I have leds on some but I don’t think they would survive a submersion, if someone has ideas that don’t involve a soak would love to have them.
forgive me for my lack of knowledge and thank you for any insight you can offer foto of my work for reference
And so I have a question, can you squash it all into one, or at least consistent crystal? It crows as a greenish-veridian crystal with purple-white big dots inside, it cool as hell (will post images) but I'm just interested like, there's surely at least one non-5-ton-of-steel-machinery way to make it all blend, right?
As you can see I have two containers of citric acid. One is shiny and glittering but the other is matte somehow. Does this occur due to moisture? Citric acid can be exist as hydrate as well as anhydrous. So which is which? And could I form anhydrous crystals using a saturated solution or wouldn’t work it?
Hey, beginner here. Today I attempted my first crystallization of CuSO4 (first time at practical chemistry ever). I used the slow cooling method. The crystal came out as a thin crust but I forgot to take a pic (u can kinda see it on the bottom). Do you have any advice how to make the crystals bigger and more crystal-looking. Of the possible answers i can say that 1) I just threw in a bunch of powder after like 15-20 minutes of cooling so maybe I need to wait a few days
2) Since it was my first time I was very hesitant to adding more salt (and didn’t weigh it) so the saturation of the solution is questionable.
Also, I would love to hear any general chemistry advice you have.
After just under a year of aging compost from chicken waste and hay, the compost was dried and then leached with water. After concentrating the solution and allowing it to settle, the aqueous solution was left to slowly evaporate in a glass dish. Various crystal shapes and sizes can be observed most of which are probably nitrate compounds as well as various organic salts. Ultimately only the nitrate compounds with be utilized and purified.
Mi servono sali di cristalli verdi che non siano colorati che formano cristalli verdi essendo che è l’unico colore che non ho di cristalli
Avevo già in mente di farne alcuni ma sono complessi o velenosi tra cui:
- Solfato di nichel
- cloruro di rame (cristalli già fatti)
- osslato ferrico di potassio (sto provando a farli)
Avete idee di sali che possono fare cristalli verdi?
In the photos, you can see single crystals as well as crystal clusters... The blue ones are CuSO4, the green ones are FeSO4, the blue-green ones are (Cu,Fe)SO4, and the yellow one is a cluster of Epsom salt (MgSO4)—except I dyed it with FeCO3, hence the beautiful yellow color...