After having my hand at that piece of Opal last month I've been itching to try out some of the local Red Rocks here in Sedona, so I found this chunk in my yard and after sitting and listening to it I heard an old man with a groovy hat and beard say, "hi there"!
I was surprised to find how hard and dense this red rock was though and my cheap little wood files didn't even scratch it, so I started with my crappy homemade chisel and a mason blade on my skill saw, and then eventually went and bought a basic stone chisel and a grinding stone for my dremel for the tight spots.
I love leaving pieces of the rock untouched, so the hat is already done! Once I'm done I'll sand it real good and add some wax to bring out the red color on the face, but leave the rest natural.
Leonardo Da'Vinci here I come!