In 1976, the Louisiana Legislature adopted as the State's gemstone Agate, a variety of translucent microcrystalline quartz called “chalcedony,” which is characterized by well-defined banding. This might be confusing, because scientifically agate is considered a variety of the mineral Quartz. Minerals are the building blocks of rocks. Agate is considered both a mineral (cryptocrystalline Quartz) and a rock, and is formed by chemical precipitation from silica-rich solution in rock cavities. Agates are found within the Citronelle Formation and younger sediments in the Feliciana Parishes. Both Agate and cCert originally formed within limestones that covered the central United States. Erosion released the state's gemstone from these limestones, and ancient rivers carried them into Louisiana and they are still carried into Louisiana by today's Mississippi River..
The best collecting localities for Louisiana's Agate is located close to Baton Rouge. The gravel beds along the Amite River are the primary collecting locality for this Louisiana gem. In this specific location a variety of banded Agate is quite common.
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Minnesota and Nebraska have also named the Agate as their State gemstone, but selected specific varieties. And like Texas, Louisiana has also named Petrified Palmwood as its State rock.
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