40×30 Cabochon; Petrified Palm Wood from Texas – Comes from palm trees from Oligocene Epoch – Around 20 to 40 million years ago. Petrified palm wood is a type of chalcedony. Petrified Palm wood is a group of fossil woods that contain prominent rod-like structures within the regular grain of the silicified wood. Depending upon the angle at which they are cut by fracture, these rod-like structures show up as spots, tapering rods, or continuous lines.