Why are some rocks magnetic?
Show answer & explanation
Answer: Iron minerals align when cooling
Pressure underground creates field — Wrong. Pressure doesn't create magnetism in rocks. Magnetic properties come from iron-containing minerals aligning with Earth's magnetic field while cooling.
Ancient iron tools buried inside — Wrong. Natural magnetic rocks formed millions of years ago from volcanic activity, not buried human artifacts.
Iron minerals align when cooling ✓ — Correct! When lava cools into rock, iron-rich minerals (like magnetite) act like tiny compass needles, aligning with Earth's magnetic field. Once solidified, this 'fossil magnetism' is locked in. Scientists study these paleomagnetic records to track how Earth's magnetic field has changed and even reversed!
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