Chalcedony is a catch all term that includes many well known varieties of cryptocrystalline quartz gemstones. Chalcedony includes Agate, Bloodstone, Carnelian, Chert, Chrysoprase, Flint, Fossil Coral, Heliotrope, Jasper, Onyx, Sardonyx, Sard, Petrified Wood, and Petrified Dinosaur Bone just to name a few of the better known varieties.
Lithostrotionella, preserved as the siliceous mineral Chalcedony, was designated by the West Virginia House on March 10, 1990, as the state gemstone. It is found in the Hillsdale Limestone formations in portions of Greenbrier and Pocahontas counties and is often cut and polished for jewelry and for displays. Lithostrotionella is technically a silicified Mississippian Fossil Coral. This coral and many other varieties lived about 340 million years ago, during the Mississippian Period, at a time when the state was encroached on by a shallow sea. In addition to corals, this sea hosted a teeming fauna of brachiopods, trilobites, and fish. When the coral died, it became saturated with water which contained a dissolved mineral called silica. The silica replaced the coral's decaying soft parts. In other words, the coral became silicified or mineralized. This West Virginia Chalcedony occurs in a variety of colors, but primarily in blue-white, grey-tan, yellow and brown in the Hillsdale location..