Petrified palmwood was designated the state fossil of Louisiana in 1976. 100 million years ago, what is now Louisiana was a lush tropical forest. Trees that fell into mineral-rich mud before having a chance to decay became petrified wood, which is actually a quartz-like stone. The organic wood cells were replaced over time by minerals, often retaining the detailed shape of the original prehistoric wood. Petrified wood is called the most beautiful of fossils.

Picture of rough petrified palmwood from:
Bernardine's - Petrified Palmwood Facts

The spotted look of palmwood is caused by fossilized rod-like structures within the original wood. Depending upon the angle the stone is cut, they show up as spots, tapering rods, or lines. Petrified palm wood is very hard and takes a wonderful polish, making beautiful jewelry. Petrified wood is also the state stone of Texas, the state gem of Washington, and the state fossil of North Dakota.