Crystal Growing
Crystal growing is a fun and educational hobby; you can produce some beautiful crystals and learn a lot about chemistry and the structure of matter into the bargain. The crystal growing recipes detailed below are mostly substances that are readily available in the home (e.g., bakery products), which don't require any technical apparatus you couldn't find in your kitchen. A lot of this stuff is suitable for kids to try, but where there are steps which are a little dangerous I've pointed them out, and they should be carried out by an adult. I've also included plenty of higher-level stuff, including references to scientific literature, to appeal to more academically minded people. The very keen amateur can try making their own goniometer, a device for measuring the angles between adjacent crystal faces; these angles can be used to calculate the relative dimensions of the crystal's building blocks, the crystallographic unit cell.
You don't need to understand the technical aspects of symmetry or space-groups to enjoy crystal growing, but this activity can lead to a greater appreciation of the order in nature. And it is VERY satisfying to grow a good-quality crystal! In addition to the information on this page, it's well worth reading Crystals and Crystal Growing, by Alan Holden and Phyllis Morrison, and/or Crystal Growth in Gels, by Heinz Henisch.
The tabbed boxes further down this page provide a lot of detailed structural and crystallographic information; I am therefore writing a brief introduction to crystal growing techniques, and the way in which crystal morphology is formally described, including an ever-growing glossary. This page has been a 'work-in-progress' for the best part of the last eight years, so it's always worth checking back for new stuff.
The dynamic atomic structure applets are implemented in Jmol, an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/
The crystal morphology models of are implemented in KrystalShaper applets. Below is an example of a 2 cm-long copper sulfate pentahydrate crystal, an illustration showing the indexing of the faces (drawn from a model constructed in KrystalShaper), and a dynamic model of the same crystal. Right click to rotate the model, left click to zoom, or click on the [Menu] for other options.
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Follow these links for crystal growing recipes
 Table salt (NaCl, halite) |
Rochelle salt (K·Na·C4H4O6·4H2O) |
| Epsom salt (MgSO4·7H2O, epsomite) |
Fritzsche's salt (MgSO4·11H2O, meridianiite) |
| Potash Alum (K·Al·(SO4)2·12H2O) |
Copper vitriol (CuSO4·5H2O, chalcanthite) |
| Nickel vitriol (NiSO4·7H2O, morenosite) |
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| Cane sugar (C12(H2O)11, sucrose) |
Fruit sugar (C6(H2O)6, fructose) |
| Bicarbonate of soda (NaHCO3, nahcolite) |
Cream of Tartar (K·H·C4H4O6) |
| Washing soda (Na2CO3·10H2O, natron) |
For those with a more analytical interest in crystallography, I've prepared a list of substances that can be grown at home without too much difficulty - either in aqueous solution or in a gel - by crystal class. There are seven crystal systems; that is, seven fundamentally different shaped blocks from which crystals may be built, known as the unit-cell. These systems are further subdivided according to the combination of symmetry elements present in the unit-cell to give the 32 crystal classes - listed under the various tabs below. Some of the examples are harder to grow than others, and not all are particularly good examples of their symmetry class; certain classes are infrequently represented in the natural world and some have no examples that can be readily crystallised at home. For example, fully 17.4 % of inorganic substances crystallise in class 2/m (the commonest by far), yet only 0.2 % of inorganic crystals fall into class 4. Prior to the development of diffraction techniques for the analysis of crystal structures, study of the morphology, and measurement of the interfacial angles (goniometry), formed the foundation of crystallography. Even without a laboratory diffractometer, morphological study of macroscopic crystals can give an amazing insight into the microscopic structure of solids.
| Crystal class | Examples you can grow |
| m3m | Sodium chloride | halite Ammonium chloride | sal ammoniac |
| m3 | Potassium aluminium sulfate dodecahydrate† | K-Alum |
| 43m | - |
| 432 | - |
| 23 | Sodium bromate† Sodium chlorate† |
† The method for growing these crystals appears in the book Crystals and Crystal Growing
| Crystal class | Examples you can grow |
| 6/mmm | Ice |
| 622 | - |
| 6m2 | - |
| 6mm | - |
| 6/m | - |
| 6 | - |
| 6 | - |
† The method for growing these crystals appears in the book Crystals and Crystal Growing
| Crystal class | Examples you can grow |
| 3m | Sodium nitrate† | nitratine |
| 32 | Calcium chloride hexahydrate | antarcticite |
| 3m | Trisodium lithium chromate hexahydrate† |
| 3 | - |
| 3 | - |
† The method for growing these crystals appears in the book Crystals and Crystal Growing
| Crystal class | Examples you can grow |
| 4/mmm | - |
| 422 | Nickel sulfate hexahydrate† | retgersite |
| 42m | Carbonyl diamide | urea |
| 4mm | - |
| 4/m | Calcium oxalate dihydrate | weddellite Calcium copper acetate hexahydrate† | paceite |
| 4 | - |
| 4 | Magnesium borate trihydrate | pinnoite |
† The method for growing these crystals appears in the book Crystals and Crystal Growing
| Crystal class | Examples you can grow |
| mmm | Potassium nitrate | niter Potassium ferricyanide† |
| 222 | Magnesium sulfate heptahydrate | epsomite Nickel sulfate heptahydrate† | morenosite Fructose Potassium bitartrate Strontium formate dihydrate† |
| mm2 | Lithium acetate dihydrate |
† The method for growing these crystals appears in the book Crystals and Crystal Growing
| Crystal class | Examples you can grow |
| 2/m | Iron sulfate heptahydrate | melanterite Sodium sesquicarbonate dihydrate | trona Sodium borate decahydrate | borax Copper acetate monohydrate† | hoganite |
| m | Sodium carbonate decahydrate | natron |
| 2 | Potassium sodium tartrate tetrahydrate† | Rochelle salt Sucrose Tartaric acid |
† The method for growing these crystals appears in the book Crystals and Crystal Growing
| Crystal class | Examples you can grow |
| 1 | Copper sulfate pentahydrate | chalcanthite Magnesium sulfate undecahydrate | meridianiite |
| 1 | - |
Table salt (sodium chloride)
Cane sugar, (sucrose)
Fruit sugar, (fructose)
Sodium bicarbonate (nahcolite), NaHCO3
Cream of Tartar (potassium hydrogen tartrate), KHC4H4O4
Washing soda (natron), Na2CO3·10H2O
Epsom salt (epsomite), MgSO4·7H2O
Fritzsche's Salt (meridianiite), MgSO4·11H2O
Rochelle Salt, KNaC4H4O6·4H2O
Potash Alum, KAl(SO4)2·12H2O
Copper vitriol (chalcanthite), CuSO4·5H2O
Nickel vitriol (morenosite), NiSO4·7H2O