Bests & Worsts Reviews from Amazon

Lots of fun with this rock collection. There's a little bit of everything: polished stones, fossils, volcanic rocks, geodes, rough rocks. Just a little bit of advice; don't toss the limestone rocks just because they look like something from your backyard! Put them in a plastic cup or a small glass jar with just enough distilled white vinegar to cover them. They will fizz like crazy for a while because limestone contains calcium carbonate which reacts with the acid in the vinegar. Let them sit undisturbed for a few days, and as the vinegar evaporates, crystals will form on the limestone rocks.