rocks are neat. God makes lots of pretty rocks. When you have some time, go visit a rock shop. it's amazing at the different shapes & kinds & bright colors of rocks available.
some rocks like sheelite (did I spell that correctly?) and some others will glow different bright colors under a UV lamp.
some rocks contain crystals that are really beautiful to look at, and some are just plain valuable. If you want to see a big chunk of purple amethyst, go to one of those nature shops. to get the real beauty out of a rock, you usually have to wet it slightly, unless they are polished stones.
Then there's petrified wood. petrification takes a short amount of time. at drdino.com (he has a museum) Dr. Hovind has lots of petrified objects. he has a picture of a petrified miners hat, he has a petrified pickle, and many other petrified objects people have sent to him. petrification takes a short amount of time.
Petrified wood you can see the grain of the wood in what is now rock. and it's different shades of brown. cool stuff. here is some petrified wood:
Here is another rock, I forget what it is, but I don't think it is cobalt. maybe it was.