Polished River Stones What Kind Of Gem Stone Did I Find?

What kind of Gem Stone did I find? - polished river stones

I have a precious stone, big enough, near a river in Oregon, but I'm not sure what kind of stone it is.
Here are some links to pictures of the precious stone, inside and out (not a piece of the stone is polished):
http://i663.photobucket.com/albums/uu360/MonkeeKing/gemstones018.jpg

http://i663.photobucket.com/albums/uu360/MonkeeKing/gemstones007.jpg

http://i663.photobucket.com/albums/uu360/MonkeeKing/gemstones048.jpg

http://i663.photobucket.com/albums/uu360/MonkeeKing/gemstones005.jpg

If anyone can help me to understand what kind of stone, I think it would be great!