r/crystalgrowing Jun 16 '20

Information The Beginner's Guide to Crystal Growing

750 Upvotes

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.

  1. Weigh 9g of alum and dissolve it in 50 ml of hot water.
  2. Stir the solution until all the salt has dissolved. If some salt refuses to dissolve, you might have to reheat the solution.
  3. Filter the solution with a coffee filter into a shallow dish.
  4. 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.
  5. Wait 1-2 days for small crystals to form. OR
  6. Sprinkle a few grains of alum powder into your solution to induce small crystals to form.
  7. 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

  1. Weigh 22g of alum and dissolve it in 100 ml of hot water to form a supersaturated solution.
  2. Stir the solution until all the salt has dissolved. If some salt refuses to dissolve, you might have to reheat the solution.
  3. Filter the solution with a coffee filter into a jar.
  4. Wait for the solution to cool to room temperature.
  5. 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.
  6. Tie the other end to a pencil/stick.
  7. Slowly immerse the seed crystal until it is suspended in the solution in your jar.
  8. Loosely cover the top of the jar.
  9. Keep it in an undisturbed place.
  10. Wait for your crystal to grow.

Method II: Evaporation

  1. Weigh 18g of alum and dissolve it in 100 ml of hot water.
  2. Stir the solution until all the salt has dissolved. If some salt refuses to dissolve, you might have to reheat the solution.
  3. Wait for the solution to cool to room temperature.
  4. Sprinkle some alum powder into the solution to induce crystals to form.
  5. Wait 2 days.
  6. Filter the solution using a coffee filter into a jar. We want the saturated solution. The crystals formed from Step 4 are not important.
  7. 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.
  8. Tie the other end to a pencil/stick.
  9. Slowly immerse the seed crystal until it is suspended in the solution in your jar.
  10. Loosely cover the top of the jar.
  11. Keep it in an undisturbed place.
  12. 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

  1. When you are satisfied with the size of your crystal, remove it from solution.
  2. Dry it with tissue paper/filter papers. Do not wash it or you will cause it to dissolve.
  3. 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

· Dmishin's crystal growing collection - lots of interesting compounds and how to synthesize them

FAQ

Check if your question is here. Click on this link to be redirected to the answers.

· Can I dye my crystals?

· My crystal was growing well, then it dissolved! What happened?

· Does the string get stuck in the crystal?

· Crystals are supposed to be shiny and transparent. Why is mine ugly and opaque?

· How do I grow a crystal cluster instead of a single crystal/vice versa?

· How can I store my crystals properly?

· Can I grow crystals on objects like rocks and bones?

· I’m concerned about safety. What should I do?

· Is the purity of my chemicals important?

· What are other chemicals I can grow crystals with?

· Is this hobby expensive?


r/crystalgrowing 1d ago

Question Ho un dubbio! cristalli dendritici misteriosi nella mia soluzione di acetato e solfato di rame. Cosa potrebbero essere?

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5 Upvotes

Sto facendo crescere dei cristalli di acetato di rame, ma nella soluzione sono comparsi anche del solfato di rame, probabilmente perché nell'aceto c'era metabisolfito di potassio che con l'aggiunta di acqua ossigenata è diventata solfato; e dei cristalli dendritici che ho notato al microscopio dopo che ho fatto asciugare una goccia di soluzione per vedere che sali c'erano dentro.

Nelle prime due foto si vedono molto bene i dendriti, nella terza due piccoli cristalli di solfato di rame (sopra) e di acetato di rame (sotto).

Sospetto della presenza di un quarto sale per via della presenza di piccole sferule trasparenti disseminate per tutto il resto della goccia.

Qualcuno sa cosa potrebbero essere i dendriti e le sferule? grazie mille


r/crystalgrowing 1d ago

Unknown precipitate in Copper (II) Sulfate solution.

2 Upvotes

I made a batch of copper sulfate solution and realized it was too dilute. So I heated it to remove the excess water. It got to boiling but after losing some of the water, it mostly stopped boiling and started to precipitate some white or maybe light blue powder out. It would also have really violent bubbles sometimes happen that would shake the whole beaker and actually knocked it off the hotplate. (Very fun to clean up all that blue btw...) Does anyone know what that precipitate could be? This was at 100C and nowhere near saturated for that temp.

ETA: It could be a dissolved impurity but I did filter all of this. It was stored as granular crystals in an open container near lots of powdered carbon(not what the precipitate was) and powdered fluoride of some kind, but also tons of dust and other detritus got into the open container.


r/crystalgrowing 1d ago

Question Borax Crystals

3 Upvotes

I wanted to make crystals using borax from the grocery but after recently reading how toxic it is I was wondering if the steam from boiling it is dangerous to inhale. I have 4 cats, two with sensitive noses and I don't want to stress them out.


r/crystalgrowing 2d ago

Beautiful crystal

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3 Upvotes

K0.95(NH4)0.05(Cr0.97Al0.02Fe0.01)(SO4)2 · 12H2O in lots of Mohr salt


r/crystalgrowing 3d ago

Image Still growing

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19 Upvotes

Sitting on a shelf for 10 weeks now undisturbed.


r/crystalgrowing 3d ago

Question How to dissolve oxalic acid

3 Upvotes

Can anyone tell me how to dissolve oxalic acid when making NaMg? I put everything into the solution at once and now it hasn't dissolved completely. What should I do?


r/crystalgrowing 2d ago

I am atempting to create sapphire, i am stuck

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1 Upvotes

r/crystalgrowing 3d ago

Question What type of Crystal should I grow if I want it to be hard enough that I could use it on a resin geode project? Usually I just buy quartz points but they are getting expensive so I would like to make my own

2 Upvotes

I would like to create a planter that looks like a geode around the edges and the quartz points are getting too expensive for my projects so I'm looking into growing my own


r/crystalgrowing 4d ago

Image Growing Green

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6 Upvotes

All grown at home by me


r/crystalgrowing 5d ago

Question Making crystals strong enough for Jewelry?

8 Upvotes

Does anyone have any tips or ideas on crystals (or really any sort of gem) that can be made at home and would be strong enough for e.g. a ring? Obviously most that are grown from solvent evaporation are pretty soft, but are there any that have postprocessing methods to make them stronger or any sort of composites we can make?


r/crystalgrowing 5d ago

Growing Crystals From Sea Water?

7 Upvotes

Hi All!

I'm an artist and I'm wanting to make some sculptures and grow salt on them using salt water. I'm in Central Florida and have access to both coasts relatively easily and was going to go and gather some seawater, submerge my pieces, and ideally they would get some salt crystals grown on them.

I've never grown crystals before and would love any advice, tips, or even just any thoughts you might have.


r/crystalgrowing 5d ago

Update of my calcium acetate

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22 Upvotes

Look at those cute spiky crystals.


r/crystalgrowing 6d ago

My Copper acetate crystals. Any tipps?

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26 Upvotes

r/crystalgrowing 6d ago

Help foster love of crystals and science

2 Upvotes

I’m visiting with my daughter this weekend, and she absolutely loves crystals! We decided to grow some Epsom salt crystals for fun as a way to tip toe into the science behind them. Do you have any tips to help make our little experiment a rousing success?


r/crystalgrowing 7d ago

Image Copper crystals that have been growing for 52 days

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75 Upvotes

Initial eectrolyte concentration of 100 g CuSO4•5H2O and ~50 g of H2SO4 per liter.

Voltage slowly increased from .3 V to .46 V.


r/crystalgrowing 7d ago

I coated the crystals with lacquer and carefully sealed them in airtight bags, labeling what was what...

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76 Upvotes

r/crystalgrowing 8d ago

Calcium acetate

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47 Upvotes

I want to produce, 1. Some acetone from scratch and 2. Possibly some nice calcium acetate crystals. This solution was done by dissolving some limestone in 25% acetic acid. It finally starts to crystallize out after a long time evaporating.


r/crystalgrowing 8d ago

Question Potassium dichromate tips?

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8 Upvotes

Hi! I've been sitting on this bottle of Potassium dichromate for a few years with the intention of making crystals with it.

I have the beaker and I technically know how to create the oversaturated solution to create seeds and crystals, but I was wondering if anyone has grown crystals with this before and has any tips for me?

Also: OF COURSE I'll use all the PPE!


r/crystalgrowing 9d ago

Im finished my summer work!!!(Copper acetate,Calcium acetate,Copper-calcium acetate,Copper sulphate,Ferrous sulphate)

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70 Upvotes

r/crystalgrowing 9d ago

Question I have finally made the iron potassium oxalate!

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17 Upvotes

Stranante mi è riuscito alla prima volta e spero che vengano dei cristalli verdi bellissimi!
Avete consigli su come farli crescere/conservarli?


r/crystalgrowing 9d ago

Image Very interesting salt NaCl needle like crystals grew in a leftover container. Around 1-2mm in length, visibly thinner than a human hair

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13 Upvotes

r/crystalgrowing 9d ago

Image I think i did something wrong (beginner)

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11 Upvotes

I thought that leaving a little hole would help with water evaporation


r/crystalgrowing 10d ago

Image Magnesium sulfate, grown suspended for a month or so

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223 Upvotes

r/crystalgrowing 11d ago

Image Managed to grow a perfect crystal of NaCl!

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1.9k Upvotes