If you're looking for an example of just how cool nature can be, look no further than picture jasper. This piece is actually called Biggs blue picture jasper, and it comes from Biggs Junction, OR on the Deschutes River. The jasper is no longer mined.
Jasper is a form of microcrystalline quartz, and the images formed in the rocks and slabs are dendritic crystal formations and fossilized mud flow. Nature, it seems, is a fabulous artist, as it naturally painted this "tree" and left it for millions of years to be discovered, slabbed, and polished.
Some indigenous populations believed the images in picture jasper were messages from the Earth coming from an ancient past, and they used it as a stone to lead them on shamanic journeys.
Metaphysically, picture jasper is used for grounding and as a stone of protection and courage. It's also a good meditation stone as it connects the meditator with Earth energies.