File:Fossil Wood (Morrison Formation, Upper Jurassic; Escalante Petrified Forest State Park, Utah, USA) 50.jpg
This type of fossil wood is usually referred to as "petrified wood". It's a preservation style actually called "permineralization" - the small-scale porosity of buried wood or bone gets filled with minerals as groundwater percolates through. The most common permineralization mineral is quartz (SiO2). Cellular-level details can be preserved in permineralized wood, but some examples have little original botanical structure remaining.
Stratigraphy: Brushy Basin Member, Morrison Formation, Upper Jurassic
Locality: trailside, Escalante Petrified Forest State Park, Utah, USA