This is a hand cut limb casting with beautiful shades of tan, red & white.  It is from Oregon.  A Limb cast is when the wood tree limb buried and the wood is burned away by hot ash.  The hollow that is left is filled with silica and calcedony which hardens into the shape of the limb.  It's not petrified wood but it is the cast of the wood from a tree limb.  They are unique and lovely, like petrified wood, but are not actually the wood itself that has petrified.  
 
This piece is 2.5" x 1.75" and is wrapped in a copper weave that has been patinated for a beautiful effect.