Petrified Palmwood

Petrified palmwood is Louisiana's official state fossil, designated in 1976. The same designation also made it the state stone — the only symbol in Louisiana's official list to hold both titles. The fossils are the silicified remains of palm trees that grew in a warm, wet coastal plain covering central Louisiana during the Oligocene epoch, roughly 30 million years ago.

Palmoxylon is not a single species name but an organ genus — a scientific category used for any fossil palm wood with the characteristic internal pattern of scattered vascular bundles. The actual parent palm species that produced Louisiana's specimens has not been determined.

In life, these were palm trees growing in the subtropical lowlands and river margins of Oligocene Louisiana, in a climate similar to today's Gulf Coast but warmer and wetter. The trunks were replaced over millions of years by silica carried in groundwater, molecule by molecule, until the original wood was completely converted to stone while the internal structure remained intact.

The defining feature of palm wood — fossil or living — is visible in cross-section: dozens of small, oval vascular bundles scattered throughout the trunk tissue rather than arranged in rings as in oak or pine. In a polished slice of Palmoxylon, these bundles appear as small rod-like or eye-shaped spots distributed across the surface, giving each piece a distinctive spotted or freckled pattern.

Palmoxylon specimens in Louisiana are found as logs, trunk sections, and fragments, often silicified in shades of tan, gray, brown, and occasionally red. The silica replacement preserves the surface texture and internal anatomy so precisely that the wood grain is often still visible on the outside of the specimen.

Louisiana designated petrified palmwood as both its state stone and its state fossil in 1976, a dual recognition that reflects how the material sits between the two categories: it is a rock (silicified stone) that was once a living organism. No other Louisiana state symbol holds both designations.

The choice was grounded in the fossil's visibility and regional identity. Petrified palmwood specimens turn up across central and northern Louisiana, and polished slabs have been sold in rock shops and collected by hobbyists across the state for generations. Its subtropical origin also fits Louisiana's modern climate: palms still grow across the state today, and the fossil version shares the same distinctive scattered-bundle trunk structure as the living ones.

Petrified palmwood is found primarily in the Catahoula Formation, an Oligocene sequence of sandstone, siltstone, and volcanic ash laid down by rivers and coastal plains across central and northern Louisiana about 30 million years ago. The formation outcrops across a broad band running through Winn, Grant, LaSalle, and Caldwell parishes, where the fossils weather out of exposed banks and hillsides.

The Kisatchie National Forest in central Louisiana lies within the main Catahoula outcrop zone and has historically been a source of palmwood specimens. Collectors find pieces ranging from small fragments to large trunk sections. The silica-hardened wood resists erosion better than the surrounding sandstone, so it tends to sit on the surface after the matrix erodes away.