Crystal Recipes - DOC by zo170CH


									How to Grow Great Crystals
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.

Tip, Tricks, and Techniques
Do you want to grow great crystals? These are general instructions for growing crystals
that you can use for most crystal recipes. You can find the recipes and information on
crystal structures in the Growing Crystals section. Here are the basics, to get you started
and help you troubleshoot problems:

What Are Crystals?

Crystals are structures that are formed from a regular repeated pattern of connected atoms
or molecules. Crystals grow by a process termed nucleation. During nucleation, the
atoms or molecules that will crystallize (solute) are dissolved into their individual units in
a solvent. The solute particles contact each other and connect with each other. This
subunit is larger than an individual particle, so more particles will contact and connect
with it. Eventually, this crystal nucleus becomes large enough that it falls out of solution
(crystallizes). Other solute molecules will continue to attach to the surface of the crystal,
causing it to grow until a balance or equilibrium is reached between the solute molecules
in the crystal and those that remain in the solution.

The Basic Technique

      Make a saturated solution.
      Start a garden or grow a seed crystal.
      Continue growth.

In order to grow a crystal, you need to make a solution which maximizes the chances for
the solute particles to come together and form a nucleus, which will grow into your
crystal. This means you will want a concentrated solution with as much solute as you can
dissolve (saturated solution). Sometimes nucleation can occur simply through the
interactions between the solute particles in the solution (called unassisted nucleation), but
sometimes it's better to provided a sort of meeting place for solute particles to aggregate
(assisted nucleation). A rough surface tends to be more attractive for nucleation than a
smooth surface. As an example, a crystal is more likely to start forming on a rough piece
of string than on the smooth side of a glass.

Make a Saturated Solution

It's best to start your crystals with a saturated solution. A more dilute solution will
become saturated as the air evaporates some liquid, but evaporation takes time (days,
weeks). You will get your crystals more quickly if the solution is saturated to begin with.
Also, there may come a time when you need to add more liquid to your crystal solution.
If your solution is anything but saturated, then it will undo your work and actually
dissolve your crystals! Make a saturated solution by adding your crystal solute (e.g.,
alum, sugar, salt) to the solvent (usually water, although some recipes may call for other
solvents). Stirring the mix will help to dissolve the solute. Sometimes you may want to
apply heat to help the solute dissolve. You can use boiling water or sometimes even heat
the solution on the stove, over a burner, or in a microwave.

Growing a Crystal Garden or 'Geode'

If you just want to grow a mass of crystals or a crystal garden, you can pour your
saturated solution over a substrate (rocks, brick, sponge), cover the setup with a paper
towel or coffee filter to keep out dust, and allow the liquid to slowly evaporate.

Growing a Seed Crystal

On the other hand, if you are trying to grow a larger single crystal, you will need to
obtain a seed crystal. One method of getting a seed crystal is to pour a small amount of
your saturated solution onto a plate, let the drop evaporate, and scrape the crystals formed
on the bottom to use as seeds. Another method is to pour saturated solution into a very
smooth container (like a glass jar) and dangle a rough object (like a piece of string) into
the liquid. Small crystals will start to grow on the string, which can be used as seed

Crystal Growth and Housekeeping

If your seed crystal is on a string, pour the liquid into a clean container (otherwise
crystals will eventually grow on the glass and compete with your crystal), suspend the
string in the liquid, cover the container with a paper towel or coffee filter (don't seal it
with a lid!), and continue to grow your crystal. Pour the liquid into a clean container
whenever you see crystals growing on the container.

If you selected a seed from a plate, tie it onto a nylon fishing line (too smooth to be
attractive to crystals, so your seed can grow without competition), suspend the crystal in a
clean container with saturated solution, and grow your crystal the same way as with seeds
that were originally on a string.

Keeping Your Treasures

Crystals that were made from a water (aqueous) solution will dissolve somewhat in
humid air. Keep your crystal beautiful by storing it in a dry, closed container. You may
wish to wrap it in paper to keep it dry and prevent dust from accumulating on it. Certain
crystals can be protected by being sealed with an acrylic coating (like Future floor
polish), although applying the acrylic will dissolve the outermost layer of the crystal.

Types of Crystals
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.

Shapes and Structures
There's more than one way to categorize a crystal! The two most common methods are to
group them according to their crystalline structure and to to group them according to their
chemical/physical properties:
Crystal Grouped by Lattices (Shape)

There are seven crystal lattice systems. You can view examples of each type by following
one of the 'Elsewhere on the Web' links I have provided.

   1. Cubic or Isometric - not always cube shaped! You'll also find octahedrons (eight
      faces) and dodecahedrons (10 faces).
   2. Tetragonal - similar to cubic crystals, but longer along one axis than the other,
      forming double pyramids and prisms.
   3. Orthorhombic - like tetragonal crystals except not square in cross section (when
      viewing the crystal on end), forming rhombic prisms or dipyramids (two pyramids
      stuck together).
   4. Hexagonal - six-sided prisms. When you look at the crystal on-end, the cross
      section is a hexagon.
   5. Trigonal - possess a single 3-fold axis of rotation instead of the 6-fold axis of the
      hexagonal division.
   6. Triclinic - usually not symmetrical from one side to the other, which can lead to
      some fairly strange shapes.
   7. Monoclinic - like skewed tetragonal crystals, often forming prisms and double

This is a very simplified view of crystal structures. In addition, the lattices can be
primitive (only one lattice point per unit cell) or non-primitive (more than one lattice
point per unit cell). Combining the 7 crystal systems with the 2 lattice types yields the 14
Bravais Lattices (named after Auguste Bravais, who worked out lattice structures in
1850). The structure of real crystals is pretty complicated! You can read about
crystallography and mineral structures here and here.

Crystals Grouped by Properties

There are four main categories of crystals, as grouped by their chemical and physical

   1. Covalent Crystals
      A covalent crystals has true covalent bonds between all of the atoms in the
      crystal. You can think of a covalent crystal as one big molecule. Many covalent
      crystals have extremely high melting points. Examples of covalent crystals
      include diamond and zinc sulfide crystals.

   2. Metallic Crystals
      Individual metal atoms of metallic crystals sit on lattice sites. This leaves the
      outer electrons of these atoms free to float around the lattice. Metallic crystals
      tend to be very dense and have high melting points.

   3. Ionic Crystals
      The atoms of ionic crystals are held together by electrostatic forces (ionic bonds).
      Ionic crystals are hard and have relatively high melting points. Table salt (NaCl)
      is an example of this type of crystal.
   4. Molecular Crystals
      These crystals contain recognizable molecules within their structures. A
      molecular crystal is held together by non-covalent interactions, like van der Waals
      forces or hydrogen bonding. Molecular crystals tend to be soft with relatively low
      melting points. Rock candy, the crystalline form of table sugar or sucrose, is an
      example of a molecular crystal.

As with the lattice classification system, this system isn't completely cut-and-dried.
Sometimes it's hard to categorize crystals as belonging to one class as opposed to another.
However, these broad groupings will provide you with some understanding of structures.
I'll test your knowledge by referring to these crystal shapes in crystal-growing tutorials!

Crystal Growing - Troubleshooting
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.

Find Out What Went Wrong
There may come a time when you will try to grow a crystal without success. Here are
some ideas for possible problems and ways to correct them:

      No crystal growth

       This is usually caused by using a solution that isn't saturated. The cure is to
       dissolve more solute into the liquid. Stirring and applying heat can help to get
       solute into solution. Keep adding solute until you start to see some accumulate at
       the bottom of your container. Let it settle out of solution, then pour or siphon the
       solution off, being careful not to pick up undissolved solute. If you don't have any
       more solute to use, you can take some comfort in knowing that the solution will
       become more concentrated over time, as evaporation removes some of the
       solvent. You can speed this process by increasing the temperature where your
       crystals are growing or by increasing air circulation. Remember, your solution
       should be loosely covered with a cloth or paper to prevent contamination, not

       If you are sure your solution is saturated, try to eliminate these other common
       reasons for lack of crystal growth:

           o   Too much vibration

               Keep your crystal setup in a quiet, undisturbed location.
       o   Contaminant in the solution

           The fix is to re-make your solution. The fix only works if you can avoid
           contamination (won't work if your starting solute is the problem).
           Common contaminants include oxides from paper clips or pipe cleaners (if
           you're using them), detergent residue on the container, dust or something
           else falling into the container.

       o   Inappropriate temperature

           Experiment with temperature. You may need to increase the temperature
           around your crystals to get them to grow (increases evaporation). For
           some crystals, you may need to decrease the temperature (which slows the
           molecules down and gives them a change to bind together).

       o   Solution cooled too quickly or slowly

           Did you heat your solution to saturate it? Should you heat it? Should you
           cool it? Experiment with this variable. If the temperature changed from the
           time you made the solution to the present time, the rate of cooling may
           make a difference. You can increase the rate of cooling by putting the
           fresh solution in a refrigerator or freezer (faster) or leaving it on a warm
           stove or in an insulated container (slower). If the temperature didn't
           change, maybe it should (heat the initial solution).

       o   Water wasn't pure

           If you used tap water, try re-making the solution using distilled water. If
           you have access to a chemistry lab, try deionized water that was purified
           by distillation or reverse osmosis. Remember... water is only as clean as its
           container! The same rules apply to other solvents.

       o   Too much light

           An unlikely problem with home crystals, but for certain materials the
           energy from light can inhibit the formation of chemical bonds.

   No seed crystals

    If you are trying to grow a large single crystal, you will need to get a seed crystal
    first. For some substances, the seed crystals may form spontaneously on the side
    of the container. For others, you may need to pour a small amount onto a saucer
    and let it evaporate to get crystals. Sometimes crystals will grow best on a rough
    string suspended into the liquid. The composition of the string is important! You
    are more likely to get crystal growth on cotton or wool string than on nylon or a

   Seed crystals dissolve when placed in new container

    This happens when the solution isn't fully saturated. See above for details.
How To Grow a Big Alum Crystal
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Alum is found in the 'spices' section of the grocery store. With a bit of time and effort, you can
   grow a big alum crystal.

Difficulty: Easy

Time Required: Days to Weeks

Here's How:

1. Pour 1/2 cup of hot tap water into a clean jar.
2. Slowly stir in alum, a little at a time, until it stops dissolving. Don't add the whole amount -
   just enough to saturate the water.
3. Loosely cover the jar with a coffee filter or paper towel (to keep dust out) and allow the jar
   to sit undisturbed overnight.
4. The next day, pour the alum solution from the first jar into the clean jar. You will see small
   alum crystals at the bottom of the jar. These are 'seed' crystals that you will use to grow a
   big crystal.
5. Tie nylon fishing line around the largest, best-shaped crystal. Tie the other end to a flat
   object (e.g., popsicle stick, ruler, pencil, butter knife). You will hang the seed crystal by
   this flat object into the jar far enough so that it will be covered in liquid, but won't touch the
   bottom or sides of the jar. It may take a few tries to get the length just right.
6. When you have the right string length, hang the seed crystal in the jar with the alum
   solution. Cover it with the coffee filter and grow a crystal!
7. Grow your crystal until you are satisfied with it. If you see crystals starting to grow on the
   sides or bottom of your jar, carefully remove your crystal, pour the liquid into the clean jar,
   and put the crystal in the new jar. Other crystals in the jar will compete with your crystal
   for alum, so it won't be able to get as big if you let these crystals grow.


1.     You can use sewing thread or other string instead of nylon fishing line, but crystals will
   grow on the entire length of the submerged string. Crystals don't adhere to nylon, so if you
   use it, you can get bigger, better crystals.
2.     Alum is an ingredient used to make pickles. It makes them crispy.

What You Need:
       1/2 c hot tap water                               2 clean jars
       2-1/2 T alum                                      spoon
       nylon fishing line                                coffee filter/paper towel
       pencil, ruler, or knife

More How To's from your Guide To Chemistry
How To Grow Borax Crystal
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Do real snowflakes melt too quickly? Grow a borax snowflake, color it blue if you like, and
enjoy the sparkle all year long!

Difficulty: Average

Time Required: Overnight

Here's How:

   1. Cut a pipe cleaner into any various lengths to create a shape you desire
   2. Twist the sections together at their centers to form a shape. Don't worry if an end isn't
      even, just trim to get the desired shape. The shape should fit inside the jar.
   3. Tie the string to the end of your shape. Tie the other end of the string to the pencil. You
      want the length to be such that the pencil hangs the shape into the jar.
   4. Fill the wide mouth pint jar with boiling water.
   5. Add borax one tablespoon at a time to the boiling water, stirring to dissolve after each
      addition. The amount used is 3 tablespoons borax per cup of water. It is okay if some
      undissolved borax settles to the bottom of the jar.
   6. If desired, you may tint the mixture with food color.
   7. Hang the pipe cleaner shape into the jar so that the pencil rests on top of the jar and the
      snowflake is completely covered with liquid and hangs freely (not touching the bottom of
      the jar).
   8. Allow the jar to sit in an undisturbed location overnight.
   9. Look at the pretty crystals!!! You can hang your shape as a decoration or in a window to
      catch the sunlight :-)

   1. Borax is available at grocery stores
   2. res in the laundry soap section, such as 20 Mule Team Borax Laundry Booster. Do not
      use Boraxo soap.
   3. Because boiling water is used and because borax isn't intended for eating, adult
      supervision is recommended for this project.
   4. If you can't find borax, you can use sugar or salt (may take longer to grow the crystals, so
      be patient). Add sugar or salt to the boiling water until it stops dissolving. Ideally you
      want no crystals at the bottom of the jar.

What You Need:
      string                                          pencil
      wide mouth jar (pint)                           boiling water
      pipe cleaners                                   blue food coloring (opt.)
      borax (see tips)                                scissors
How To Grow a Bluing Crystal Garden
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Make delicate, colorful crystals! This is a great classic crystal-growing project. You use
porous materials (i.e.charcol, sponges, rough rocks, brick, filter paper, etc), ammonia,
salt, bluing, and food coloring to grow a sort of crystal garden. The components of the
garden are toxic, so adult supervision is recommended. Be sure to keep your growing
garden away from young children and pets!

Difficulty: Easy

Time Required: 2 days to 2 weeks

Here's How:

   1. Place chunks of your substrate (i.e., charcoal briquette, sponge, cork, brick,
       porous rock) in an even layer in the non-metal pan. You want pieces that are
       roughly 1-inch in diameter, so you may need to (carefully) use a hammer to break
       the material up.
   2. Sprinkle water, preferably distilled, onto the substrate until is has been thoroughly
       dampened. Pour off any excess water.
   3. In an empty jar, mix 3 tablespoons (45 ml) uniodized salt, 3 tablespoons (45 ml)
       ammonia, and 6 tablespoons (90 ml) bluing. Stir until the salt is dissolved.
   4. Pour the mixture over the prepared substrate.
   5. Add and swirl a bit of water around in the empty jar to pick up the remaining
       chemicals and pour this liquid onto the substrate, too.
   6. Add a drop of food coloring here and there across the surface of the 'garden'.
       Areas with no food coloring will be white.
   7. Sprinkle more salt (about 2 T or about 30 ml) across the surface of the 'garden'.
   8. Set the 'garden' in an area where it will not be disturbed.
   9. On days 2 and 3, pour a mixture of ammonia, water, and bluing (2 tablespoons or
       30 ml each) in the bottom of the pan, being careful not to disturb the delicate
       growing crystals.
   10. Keep the pan in an undisturbed place, but check on it periodically to watch your
       very cool garden grow!


   1. If you can't find bluing at a store near you, it is available online: (Mrs. Stewart's Bluing).
   2. Crystals form on the porous materials and grow by drawing up the solution using
      capillary action. Water evaporates on the surface, depositing solids/forming
      crystals, and pulling more solution up from the base of the pie plate.

What You Need:
       Charcoal Briquettes (or pieces of               Food Coloring
        sponge or brick or porous rock)                 Non-Metal Pie Plate (glass is
       Distilled Water                                  great)
       Uniodized Salt                                  Measuring Spoons
       Ammonia                                         Empty Jar
       Bluing
How To Grow Sugar Crystals - Make
Your Own Rock Candy
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
It's easy to grow your own sugar crystals! Sugar crystals are also known as rock candy
since the crystallized sucrose (table sugar) resembles rock crystals and because you can
eat your finished product. You can grow beautiful clear sugar crystals with sugar and
water or you can add food coloring to get colored crystals. It's simple, safe, and fun.
Boiling water is required to dissolve the sugar, so adult supervision is recommended for
this project.

Difficulty: Easy

Time Required: a few days to a week

Here's How:

   1. Gather your materials.
   2. You may wish to grow a seed crystal, a small crystal to weight your string and
       provide a surface for larger crystals to grow onto. A seed crystal is not necessary
       as long as you are using a rough string or yarn.
   3. Tie the string to a pencil or butter knife. If you have made a seed crystal, tie it to
       the bottom of the string. Set the pencil or knife across the top of the glass jar and
       make sure that the string will hang into the jar without touching its sides or
       bottom. However, you want the string to hang nearly to the bottom. Adjust the
       length of the string, if necessary.
   4. Boil the water. If you boil your water in the microwave, be very careful removing
       it to avoid getting splashed!
   5. Stir in the sugar, a teaspoonful at a time. Keep adding sugar until it starts to
       accumulate at the bottom of the container and won't dissolve even with more
       stirring. This means your sugar solution is saturated. If you don't use a saturated
       solution, then your crystals won't grow quickly. On the other hand, if you add too
       much sugar, new crystals will grow on the undissolved sugar and not on your
   6. If you want colored crystals, stir in a few drops of food coloring.
   7. Pour your solution into the clear glass jar. If you have undissolved sugar at the
       bottom of your container, avoid getting it in the jar.
   8. Place the pencil over the jar and allow the string to dangle into the liquid.
   9. Set the jar somewhere where it can remain undisturbed. If you like, you can set a
       coffee filter or paper towel over the jar to prevent dust from falling into the jar.
   10. Check on your crystals after a day. You should be able to see the beginnings of
       crystal growth on the string or seed crystal.
   11. Let the crystals grow until they have reached the desired size or have stopped
       growing. At this point, you can pull out the string and allow the crystal to dry.
       You can eat them or keep them. Have fun!

   1. Crystals will form on a cotton or wool string or yarn, but not on a nylon line. If
      you use a nylon line, tie a seed crystal to it to stimulate crystal growth.
   2. If you are making the crystals to eat, please don't use a fishing weight to hold your
      string down. The lead from the weight will end up in the water -- it's toxic. Paper
      clips are a better choice, but still not great.

What You Need:

       1 cup water
       3 cups table sugar (sucrose)
       clean glass jar
       pencil or butter knife
       string
       pan or bowl for boiling water and making solution
       spoon or stirring rod

More How To's from your Guide To Chemistry
How To Grow Crystal Spikes in the Sun
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Most crystals take days or weeks to form. Use this technique if you have a sunny day and
want crystals FAST!

Difficulty: Easy

Time Required: 1-3 hours

Here's How:

   1. First, a sunny day isn't required, but it will help! You want rapid evaporation of
      the water to form the crystals, so select a warm, dry place to grow crystals (sunny
      porch or window is great).
   2. Use the scissors to cut black (or other dark color) construction paper so that it will
      fit in the bottom of the pan.
   3. Add 1 tablespoon of Epsom salt to 1/4 cup warm water. Stir until the salt is
   4. Put the construction paper in the pan and pour the salt solution over the paper.
   5. Put the pan in the place you have selected for crystal-growing. As the water
      evaporates, you'll see lots of spiky crystals.
   6. Have fun! Use a magnifying glass to see your creations up-close.


   1. This is one of the fastest, least toxic methods of growing crystals. You can
      substitute regular salt for Epsom, but the resulting crystals won't be as exciting.
   2. Wash your hands after handling Epsom salts. Don't drink the solution and avoid
      spilling it on yourself.
   3. Experiment with adding water colors or food color to the salt solution.

What You Need:

       black construction paper
       pie or cake pan
       warm water
       Epsom salt
       scissors

More How To's from your Guide To Chemistry
How To Grow Epsom Salt (Magnesium
Sulfate) Crystals
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
You can find epsom salts (magnesium sulfate) in the laundry and pharmacy sections of
most stores. Epsom salt crystals are safe to handle, easy to grow, and form quickly. You
can grow clear crystals or add food coloring if you prefer. Here's what you need to know
to make your own crystals.

Difficulty: Easy

Time Required: A Few Days

Here's How:

1. Boil the water in a microwave or on the stove.

2. Remove the water from heat and add the epsom salts. Stir the mixture until the salt is
fully dissolved. If desired, add food coloring.

3. Pour the mixture over a piece of sponge (optional) or into a shallow container. You
need just enough liquid to cover the bottom of the container.

4. Place the container in a warm or sunny location. Crystals will form as the water


   1. The sponge provides extra surface area to allow the crystals to form more quickly
      and helps make them a bit easier to view and handle.
   2. Compare the appearance of the epsom salts before stirring them into the water
      with the appearance of the crystals that are produced.

What You Need:

       1/4 cup epsom salts (magnesium sufate)
       1/2 cup water
       shallow bowl or dish
       sponge (optional) or other porous type material
       food coloring (optional)

More How To's from your Guide To Chemistry
How To Grow Table Salt or Sodium
Chloride Crystals
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Table salt or sodium chloride crystals are great crystals to try if you've never grown
crystals before because it's easy to find salt and water (the ingredients), the crystals are
non-toxic, and no special equipment is required. Let's get started!

Difficulty: Easy

Time Required: a few hours to several days, depending on your method

Here's How:

1. Stir salt into boiling hot water until no more salt will dissolve (crystals start to appear
at the bottom of the container). Be sure the water is as close to boiling as possible. Hot
tap water is not sufficient for making the solution.

2. If you want crystals quickly, you can soak a piece of cardboard in this supersaturated
salt solution. Once it is soggy, place it on a plate or pan and set it in a warm and sunny
location to dry out. Numerous small salt crystals will form.

3. If you are trying to form a larger, perfect cubic crystal, you will want to make a seed

4. To grow a big crystal from a seed crystal, carefully pour the supersaturated salt
solution into a clean container (so no undissolved salt gets in), allow the solution to cool,
then hang the seed crystal in the solution from a pencil or knife placed across the top of
the container. You could cover the container with a coffee filter if you like.

5. Set the container in a location where it can remain undisturbed. You are more likely
to get a perfect crystal instead of a mass of crystals if you allow the crystal to grow
slowly (cooler temperature, shaded location) in a place free of vibrations.


   1. Experiment with different types of table salt. Try iodized salt, uniodized salt, sea
      salt, or even salt substitutes. Try using different types of water, such as tap water
      compared with distilled water. See if there is any difference in the appearance of
      the crystals.
   2. If you are trying for the 'perfect crystal' use uniodized salt and distilled water.
      Impurities in either the salt or water can aid dislocation, where new crystals don't
      stack perfectly on top of previous crystals.

What You Need:
       table salt - sodium chloride
       water
       clean clear container
       piece of cardboard (optional)
       string and pencil or butter knife (optional)
How To Grow Purple Chromium Alum
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Learn how to grow deep purple or lavender cubic crystals of potassium chromium
sulphate dodecahydrate. In addition, you can grow clear crystals around the purple
crystals, yielding a sparkling crystal with a purple core. The same technique can be
applied to other crystal systems.

Difficulty: Average

Time Required: days to months depending on desired size

Here's How:

   1. The growing solution will consist of a chromium alum solution mixed with an
      ordinary alum solution. Make a chromiun alum solution by mixing 60 g of
      potassium chromium sulfate in 100 ml water (or 600 g chromium alum per liter of
   2. In a separate container, prepare a saturated solution of ordinary alum by stirring
      alum into warm water until it will no longer dissolve.
   3. Mix the two solutions in any proportion that you like. The more deeply colored
      solutions will produce darker crystals, but it will also be harder to monitor crystal
   4. Grow a seed crystal using this solution, then tie it to a string and suspend the
      crystal in the remaining mixture.
   5. Loosely cover the container with a coffee filter or paper towel. At room
      temperature (~25°C), the crystal can be grown via slow evaporation for as little
      time as a few days or as long as a few months.
   6. To grow a clear crystal over a colored core of this or any other colored alum,
      simply remove the crystal from the growing solution, allow it to dry, and then re-
      immerse it in a saturated solution of ordinary alum. Continue growth for as long
      as desired.


   1. A saturated solution of pure chrome alum will grow darker crystals, but the
      solution will be too dark to see through. Feel free to increase the concentration of
      chrome alum, but be aware that the solution becomes deeply colored.
   2. Notice that the chrome alum solution is a dark blue-green, but the crystals are

What You Need:
       potassium chromium sulfate                      string
        (chromium alum)                                 coffee filter or paper towel
       alum                                            pencil, knife, or stick (to suspend
       water                                            string)
       clear glass jar                                 spoon or stirring rod
How To Grow Red Potassium Ferricyanide
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Grow red crystals without dye! Potassium ferricyanide (K3Fe(CN)6), also known as 'Red
Prussiate of Potash', makes beautiful red monoclinic crystals. Don't be too concerned about the
'cyanide' part of the chemical name. You shouldn't eat your crystals or drink the liquid, but it's
safe to grow these crystals on a countertop or pour your waste down the drain.

Difficulty: Average

Time Required: one or more weeks

Here's How:

    1. Place 93 grams of potassium ferricyanide and 200 ml warm water into a clear container.
    2. Stir to dissolve.
    3. If you wish to grow a single large crystal, pour a few drops of this solution onto a saucer
       or other shallow dish (perhaps with a string laid across the liquid, otherwise tie crystals
       from the plate onto a string). Allow this liquid to evaporate to form seed crystals. Tie the
       string to a pencil or butter knife to suspend the string into the original container, being
       careful not to touch the sides or bottom of the container.
    4. Cover the container with a paper towel or coffee filter. You want evaporation to occur,
       but you don't want contaminants to be able to fall into your crystal-growing solution.
    5. Leave your solution undisturbed, but check on it from day to day to watch your crystals
    6. Once the crystals have reached the desired size (probably after a week or two), remove
       the crystal and allow it to dry on a paper towel. Once dry, you can store your crystal
       wrapped in a piece of tissue.
    7. Alternatively, you could allow all of the liquid to evaporate from the container (takes
       about a month, depending on ambient temperature and humidity).


    1. If you are having trouble getting all of the solid to dissolve, try using hotter water. If the
       solid still won't dissolve, allow the solution to settle out, then use only the clear portion
       for growing crystals (decant it or carefully pour it the solution into a clean container). If
       you have solids in your starting solution, the crystals will form (nucleate) around the
       particles and the resulting crystals will be smaller than if you used a clear solution.

What You Need:
   93 g potassium ferricyanide                                string/pencil (optional) spoon or
   200 ml warm water                                           stirring rods
   clear glass or plastic container
      coffee filter or paper towel
How To Make Peppermint Cream Wafers
From Anne Marie Helmenstine, Ph.D.,Your Guide to Chemistry.
Cooking is really an artistic variation of chemistry! Here's a fun and easy Christmas
holiday project for the chemistry lab. Make these peppermint cream wafers for a seasonal
project or demonstration.
Difficulty: Average

Time Required: 30 minutes

Here's How:

   1. First, make sure all of the measuring utensils and glassware are clean and dry. If
      possible, use beakers that have never been used for more tradition chemistry
      experiments, since residues of chemicals can remain in the glass.
   2. Measure and mix the following chemicals in a 250-ml beaker: 1/4 cup or 2
      tablespoons or 2 level medicine cups of sugar; 8 ml (1.5 tsp) milk; 10 ml (2 tsp)
      Karo syrup; 1/4 tsp or pea-sized amount of cream of tartar.
   3. Heat the mixture until its temperature reaches 200°F, stirring often.
   4. Once the temperature reaches 200°F, cover the beaker (with foil) and remove it
      from the heat for 2 minutes.
   5. Return the mixture to the heat. Heat and stir until the temperature reaches 240°F
      (soft-ball on a candy thermometer).
   6. Remove the mixure from heat and add one drop of peppermint oil and 1-2 drops
      of food coloring.
   7. Stir until the mixture is smooth, but not any longer than that or else the candy
      could harden in the beaker. Avoid stirring longer than 15-20 seconds.
   8. Pour coin-sized drops of the mixture onto a sheet of foil. Depending on the size of
      the drops, you will get 8-12 of them. Allow the candy to cool, then peel the drops
      off to enjoy your treat! Hot water is sufficient for clean-up.


   1. You can use wooden tongue depressors or metal spoons for stirring.
   2. Disposable plastic measuring cups, such as those used to dispense liquid
      medications, work well for measuring the ingredients for a lab of students.
   3. The mixture can be heated over a hotplate or a bunsen burner, with a ring stand
      and wire gauze pad. You could also use a stove.
   4. The texture of the finished product depends on the heating/cooling of the sugar
      mixture. You could get jellied candies or rock candy. It's a nice opportunity to
      discuss crystal structures.

What You Need:
       sucrose (table sugar)                         oil of peppermint
       concentrated liquid sucrose (or               250 ml beaker or a saucepan
        Karo syrup)                                   candy thermometer or other
       potassium tartrate (cream of                   metal-backed thermometer
        tartar)                                       aluminum foil
       lactose (we will use milk)                    assorted labware or utensils for
       food coloring                                  stirring,
                             When you make rock candy, you can see the shape
                             of sugar crystals on a giant scale. The key is giving
                             them lots of time (about 7 days) to grow. As the
                             water evaporates, sugar crystals form on the string
                             or stick, and the shapes that they form reflect the
                             shape of individual sugar crystals.

Learn more about sugar and crystals.

                                          Recipe Conversions

                    (Note: Recipe annotations will appear in a new window.)

                  Table sugar crystals,            Rock candy crystals,
                  magnified 100 times              magnified 250 times

                  Notice that the shapes of the rock candy crystals are
                  very similar to those of the sugar crystals. That’s
                  because rock candy is made up of many sugar crystals
                  that have grown together.
                  (Images courtesy of FEI Company)

What Do I Need?
• 4 cups sugar
• 2 cups water

• a small saucepan
• a wooden spoon
• a candy thermometer
• a small, clean glass jar
• a measuring cup
• cotton string
• a weight to hang on the string (such as a screw or galvanized washer)
• waxed paper
• a pencil (to suspend the string in the jar)
What Do I Do?
1. Heat the water in the saucepan over medium-high heat until it comes to a

2. Completely dissolve the sugar in the boiling water, stirring continuously
with the wooden spoon until the solution grows clear and it reaches a rolling

3. Remove the solution from the heat, and then carefully pour it into the jar.
Cover the jar with a small piece of waxed paper.

4. Tie the weight to one end of the string, and then tie the other end to the
middle of the pencil. The string should be about two-thirds as long as the jar
is deep. Dip the string into the sugar solution, remove it, lay it on a piece of
waxed paper, straighten it out, and let it dry for a few days.

• Why does the string need to be soaked and then dried?

5. Gently suspend the prepared string in the solution and let sit at room
temperature, undisturbed, for several days. You can check each day to see
how much your crystals have grown. It’s tempting, but don’t touch the jar
until the experiment is finished—it usually takes about seven days.

• What makes the crystals grow?
6. At the end of the week, the crystals on your string should be clearly
defined, with sharp right angles and smooth faces of various sizes. In the field
of crystallography, these are called monoclinic crystals. Their shape is
determined by the way the individual sugar molecules fit together, which is
similar to the way the shape of a pile of oranges is determined by the shape
of the individual oranges and the way they stack together.

What Else Can I Try?
• Try adding food coloring or flavoring to your sugar syrup before making the
rock candy.

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