Step 1 : Introduction to the question "2. Which rock is considered to be the lightest?"
...1. shale 2. pumice 3. hornfels 4. rhyolite Pumice is an igneous rock that is so light it can float on water. It is formed from bubbling lava. Due to its rough surface, pumice can be used as an abrasive for scouring and polishing. Pumice stones can be used to smooth rough areas on feet.
Step 2 : Answer to the question "2. Which rock is considered to be the lightest?"
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