Louisiana has a number of gemstones, minerals and fossils that attract many collectors. The state had declared petrified palm wood as the official state fossil and agate as the state gemstone in the year 1976. However, in 2011 oyster shell which is commonly found in coastal Louisiana was adopted as the state gemstone while agate was re-designated as the state mineral.
The state’s mineral, agate is usually found in the gravels and limestone deposits in Louisiana. It is found in the southeastern part of Louisiana in the area eastwards from Mississippi River towards the Amite River valley in St. Tammany Parish north of Covington and in the Clinton area of East Feliciana Parish.
The most popular collecting site is Baton Rouge and the gravel beds along Amite River. Bogue Chitto River and the Pearl River also have agates.
Petrified Palm Wood
Petrified Palm Wood is the official state fossil of Louisiana. Petrified wood is formed by a natural process over millions of years. When a palm tree died and fell, it was covered by ground water flowing on the coast or shore. Over a considerable period of time the silica solidified and replaced the natural sap throughout the tree trunk and thus produced the petrified wood or wood fossilized palm.
The palm wood found is generally of the Palmoxylon variety which once grew in the Gulf Coastal Plains in the Oligocene era, almost 30 million years ago.
Petrified Palm Wood is generally found in the parishes situated in the northern parts of Louisiana as the Gulf of Mexico is believed to have been situated in the Oligocene period much more north than its present location. The fossilized palm is available at many locations of the state and specifically in the region where the Catahoula formation consisting of sandstone, siltstone and mudstone exists.
Evenly and completely fossilized trunks are cut and polished to be used as gems, book ends, sculptures and other ornamental objects. When the cut is made along the trunk the cut pieces have an appearance of wood grains. However if the material is cut at right angles to the trunk, the appearance is that of a dotted matrix.
The palm fossils of Louisiana occur generally in colors ranging from white to brown and even chocolate to black. Few instances of pink, orange and red fossils have also been known to be found.
Louisiana adopted the cut and polished oyster shell in the cabochon cut form as the official gemstone in 2011. The crassotrea virginica mollusk is commonly available in large numbers off the coast of Louisiana. The shell of this oyster when cut in cabochon form and polished is considered as gemstone material and was designated as the new state gemstone replacing the agate.
These gemstones are primarily found in the coastal belt of Louisiana. While not technically a gemstone, they can be quite beautiful when incorporated into jewelry.
These extremely rare specimens of fossilized corals known as agatized corals can be found in the gravels of ancient and present streams. Agatized corals can look relatively dull and unattractive from the outside, but when broken open they will often show banding of a variety of beautiful colors.
This phenomenon occurs when silica in ocean water is naturally replaced by chalcedony. This process takes millions of years, and the result is a coral specimen that has literally transformed into an agate specimen.
Agatized coral is found in Louisiana as well as the other states in the Deep South.