Thermoluminescence refers to the name for the light that a mineral produces when heated. Thermoluminescence dating means when all buried material are constantly exposed to radiation; a small portion is trapped as energy. The amount of time a crystal is underneath is recorded by amount of thermoluminescence accumulated. If heat is reapplied, the energy in the crystal is released as a form of light and the amount of thermoluminescence released can be measured to calculate how much time passed since the last heating.