This is a Fossil of Bogwood from Oregon. This piece measures approx. 34  x 24 mm: thickness is approx. 7 mm: weight is 14 grams.
 
Bogwood Fossil is Gary Green Jasper or aka Larsonite. It is a form of petrified wood from a location near McDermitt Oregon. It is thought to be wood that was covered by volcanic activity between 11-15 million years ago