Effective October 1, 2004, the State Legislature named the Patuxent River Stone the State Gem of Maryland . The Patuxent River Stone is actually an Agate, a cryptocrystalline form of quartz. This particular variety found only in Maryland, the Patuxent River Stone's colors of red and yellow reflect in the Maryland State Flag.
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The Patuxent River Stone is a recently newly-discovered gemstone that has extraordinary color and has high potential as a gemstone. It also reflects the geology of Maryland and is found only in Maryland. Wisps of red and yellow, traces of bone like cell structure, and a glowing translucence make the Patuxent River Agate an excellent stone for cutting, polishing, carving, and setting into jewelry..
The gem is occasionally found in the late Cretaceous gravel of the Arundel formation, which has been mined for decades for construction material. It is silica replaced fragments of petrified bone material, mostly dinosaur bone, and is evidence of Maryland's roughly 115 million year old bay type environment. Perhaps 10,000 generations of dinosaurs are represented in the exposed Arundel formation which outcrops though the middle of the state. The petrification process amounted to infilling of bone marrow by silica and minute amounts of clay. Perhaps, there may have been some later changes in the crystal structure due to depth of burial. Recently found specimens prove that there is a link to dinosaur bones. Many of the internal bone patterns can be readily seen in the cut stones and slabs. The history of this stone itself is an asset as a gemstone. The gems can be found best in a narrow band running from Washington D.C. northeast through Baltimore and, thanks to movement by the glaciers, the gems also exist in younger sediments througout the Eastern shore area. The nature of the formation of these stones may also be connected with the Geothermal hot spots that still exist on the Eastern shore. .
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