Some minerals are extremely soft—as soft as baby powder. Other minerals are extremely hard—like diamonds, the hardest natural substance in the world. Some rocks were once extremely hot—they were made from magma deep under the earth.Do you know that you use minerals when you look in a mirror, brush your teeth, or sprinkle salt on your French fries? Find out all the answers about rocks and minerals—even how to study them yourself—when you dig in to Extreme Rocks & Minerals! Q&A.