When hot lava explodes from a volcano, it can melt just about anything in its way - but not diamond. So some cooled lava rocks have diamonds inside them! You'd have to sort through about 250 dump trucks of lava to find 1 carat of diamonds (1/141 of an ounce). But there are other materials inside lava, too. If you buy lava rocks for a grill, put a rock in a sock and smash it with a hammer (with a grown-up's help). Here at Bedtime Math we found chips of white quartz in ours. See if you find anything!