Cracking Apart

Granite chips are heated in a Bunsen flame until glowing and then rapidly cooled in cold water, simulating the physical weathering of rocks caused by extreme temperature changes in desert environments.

1. Place a small granite chip in tongs and hold it in the outer blue flame of the Bunsen burner until it glows.
2. Quickly transfer the hot chip into a beaker of cold water.
3. Repeat the heating and cooling cycle several times until the granite chip begins to crack apart.
4. Record the number of cycles required for the granite to fracture.

Granite - Physical weathering : effect of temperature change - ILC Science:

📄 Cracking apart - Earthlearningidea: https://www.earthlearningidea.com/PDF/71_Cracking_apart.pdf

• Compare weathering rates of granite with quartzite (single mineral).
• Investigate the effect of changing the temperature of the cooling water.
• Explore other physical weathering methods such as freeze-thaw cycles or wetting and drying.

• Safety glasses required.
• Handle hot rocks with tongs, never with bare hands.
• Keep hands and face away from the flame.
• Use a heatproof mat under the Bunsen burner.

• How many heating and cooling cycles were needed for the granite chip to break apart?
• How does this laboratory simulation represent natural processes in deserts?
• Where on Earth today might rocks break apart in this way?
• In what ways is this laboratory activity different from real desert conditions?
• Why would granite (containing several minerals) weather more quickly than quartzite (containing one mineral)?