Explore the nature of coral!

15 minutes


  • Put on protective gloves and eyewear.
  • Conduct the experiment on the plastic tray.
  • Take protective gloves off before lighting the splint.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

FAQ and troubleshooting

What should I do if the stone doesn’t fit into the foil?

If you can't wrap the stone in foil, don’t worry. Just use a smaller stone.

I want to repeat the experiment, but I don’t have enough foil from the set left. Can I use the foil I have in my kitchen?

Note that the first step is to cut a sheet of foil in half!

If you look closely, you’ll notice that the foil from the set is much thicker than ordinary foil. Unfortunately, this makes it difficult to replace with foil from another source.

Nothing happened at the end of the experiment. The stone didn't change colors. What should I do?

The main result of the experiment should be the stone’s smell. The stone may not change color. If there is no smell, try repeating the experiment using a smaller piece of coral and a new piece of foil!

When I removed the stone from the burner, I melted the tweezers...

Don’t worry! Just continue with the experiment.

Step-by-step instructions

Let’s see what some heat does to a piece of coral.


Use a candle as a source of heat.


Heat the coral, then cool it in water.


What happened to the piece of coral?



Dispose of solid waste along with household garbage.

Scientific description

Is coral a mineral?

Minerals are crystalline-structured chemical compounds not produced via biological processes. Even though coral may look like a mineral, it isn’t—it is an accumulating skeleton of sea animals of the same name! Moreover, coral is naturally matte; it shines only when manually polished.

What does coral consist of?

Chemically, coral consists almost entirely of calcium carbonate CaCO3—the same compound chalk is made of. Coral owes its vivid red color to natural pigments known as carotenoids. Coral’s color has made it popular for use in decorations since ancient times.

When coral is heated, a strong smell arises because of the organic remains left in the skeletal structure. Heat can also cause a slight change in coral’s color.