Glowing marble

Watch a piece of marble glow!

Difficulty:
Danger:
Duration:
10 minutes
Glowing marble

Safety

Put on protective gloves and eyewear. Conduct the experiment on the plastic tray.

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

I can’t see the marble glowing. What’s wrong?

First, make sure you are performing the experiment in a relatively dark room. The room doesn’t need to be completely dark, but the lights should be at least dimmed to make the results more easily visible.

You can also try taking the piece of marble in the holder out of the flame after 15-20 seconds. It’s easier to see the marble glowing when it’s framed against a dark backdrop instead of the fire.

Also, try holding the stone in the flame 20-30 seconds longer. Incidentally, you can take the stone out, observe it a bit (without letting it cool down completely), then continue heating it to watch it glow some more. Just keep in mind that this process will only continue for 1-2 minutes. Check out the Scientific Description section of this experiment to learn more about this phenomenon.

Step-by-step instructions

To observe thermoluminescence, take a piece of marble and some solid fuel.

calcium_marble-burning_en_iks-01

When heated, the marble releases some of the energy “locked” inside it.

calcium_marble-burning_en_iks-02

Disposal

Dispose of solid waste together with household garbage.

Scientific description

What is marble?

Marble is a rock composed mainly of calcium carbonate CaCO3, with a small amount of calcium magnesium carbonate CaMg(CO3)2.

Marble, particularly white marble, has been used in sculpture since ancient times.

Marble is also widely known for its use in famous architectural structures. For example, the fourth largest church in the world, Milan Cathedral (also known as Duomo, or Duomo di Milano), is made of thousands of marble blocks. You might also be familiar with the Taj Mahal mausoleum, with its towering marble dome.

It would be difficult to produce marble in the laboratory the same way it forms in nature – the natural processes take thousands of years under high pressures and temperatures in the Earth’s crust. And indeed, marble exhibits some interesting properties that an ordinary piece of calcium carbonate does not.

What is the glowing we observe and why does it appear?

In brief, natural marble accumulates energy during the years it exists in the earth’s crust. It is exposed to small doses of radiation over time; this doesn’t make the marble radioactive but instead lends some of the atoms in its structure a bit of extra energy.

To specify a bit, some electrons in these atoms get trapped in a so-called excited state, in which they possess more energy than normal. Most of the electrons lose this energy over time, but some of them (due to complicated reasons) do not.

When we heat our piece of marble, certain changes occur internally that allow this extra energy to escape; the electrons finally give the excess energy away, returning to their normal states. We can observe this energy release in the form of a dim orange glow.

After 1-2 minutes of exposure to heat, the piece of marble will stop glowing, as all of its excited electrons will have reverted to their non-excited or ground state.

What is solid fuel and why do we use it here?

Solid fuel is a substance called urotropine, or hexamethylenetetramine. It consists of 6 carbon C, 12 hydrogen H, and 4 nitrogen N atoms – C6H12N4.

Solid fuel burns readily with a colorless flame, producing almost no smoke or smell but releasing a lot of heat. The colorless flame and lack of smoke help us clearly see the result of this experiment.

We use this solid fuel to provide our marble sample with the energy it needs to make this experiment possible.