Polished petrified wood showing the original grain.
So-called 'petrified wood', is a common term for something that is technically called permineralised wood. Wood is fairly porous, so after burial, it can get partially or completely filled up with minerals, commonly quartz (silicon dioxide) as groundwater or rock fluids percolate through. The end result is a harder, denser material that retains the original form and detail.
Size: Hand specimen.
Locality: South Island, New Zealand.
Images are examples of specimens only. Sizes and shapes may vary.