How To Grow Sodium Nitrate Crystals

Sodium Nitrate Crystals

This is the ball and stick structure of a unit cell of a sodium nitrate crystal.
This is the ball and stick structure of a unit cell of a sodium nitrate crystal. Ben Mills

Sodium nitrate is a common chemical, found in food, fertilizer, glass enamel and pyrotechnics. Sodium nitrate, NaNO3, forms colorless hexagonal crystals. Although these crystals are a bit more challenging to grow than some of the beginner crystals, the interesting crystal structure makes them worth the effort. The crystal somewhat resembles calcite, exhibiting some of the same properties. Sodium nitrate crystals can be used to examine double refraction, cleavage and glide.

Sodium Nitrate Crystal Growing Solution

First prepare a supersaturated solution.
  1. Dissolve 110 grams sodium nitrate per 100 ml hot water. This will be a supersaturated solution. One method of growing crystals is to allow this solution to cool in an undisturbed location and allow it to produce crystals as the liquid evaporates.
  2. Another method of growing this crystal is to grow a single crystal in a sealed contained from a supersaturated solution. If you choose to follow this method, prepare the aforementioned solution, allow this solution to cool, then add a couple of grains of sodium nitrate and seal the container. The excess sodium nitrate will deposit on the grains, producing a saturated sodium nitrate solution. Allow a couple of days for this to occur.
  3. Pour off the saturated solution. Pour a small amount of this solution into a shallow dish. Allow the liquid to evaporate, to produce small seed crystals. Select a crystal or two for further growth.
  1. To prepare the supersaturated growing solution, to your existing solution add 3 grams of sodium nitrate per 100 ml of water in the original solution. So, if you prepared 300 ml of solution, you would add an extra 9 grams of sodium nitrate.
  2. Carefully add your seed crystal to this liquid. You can suspend the crystal from a nylon monofilament. A nylon monofilament or wire is used because it won't wick up solution, causing evaporation.
  1. Seal the jar and allow the crystals to grow at a constant temperature, someplace they won't be disturbed. Sodium nitrate is very sensitive to temperature changes, so maintaining a constant temperature is important. If you have difficulty maintaining a temperature, you can place the sealed jar inside a water bath. If you don't see crystal growth after a few days, try lowering the temperature slightly.

Learn More

How To Grow a Seed Crystal
Crystal Growing Recipes
Crystal Chemicals