Kentucky lies in the southeastern part of the United States. Towards the northern border of the state, flows the Ohio River surrounded by the Ohio Valley.
The valley is primarily composed of sedimentary rock resulting only in a few minerals such as fluorite, calcite, quartz, dolomite, geodes and pyrite. Kentucky has vast deposits of coal. Agates, freshwater pearls and fossils are also present in the state.
In 1986, freshwater pearls were designated as the official state gemstone. Pearls are formed by organisms such as oyster, clam or mussel that live in saltwater or freshwater. These organisms release and surround themselves with a substance called nacre often called as mother of pearl in order to get rid of irritants that get accumulated in their shell. The irritant is mostly sand grains, dirt or a parasite. The organisms continue to add layers of the substance until they are alive resulting in the formation of the pearls.
Freshwater pearls can be found in the Tennessee River Valley and the Mississippi River Valley of Kentucky.
Agate was declared as the official state rock of Kentucky. The agates in Kentucky can be found in the counties of Jackson, Powell, Estill, Rockcastle and Madison. The agates are particularly present around exposed areas of the Borden Formation alongside creeks and drainages.
Geodes are found in abundance in the south central part of Kentucky. One of the prime locations where geodes are found is at the formations of Warsaw-Salem and the Fort Payne. The creeks present in these formations are the source of numerous geodes.
Geodes can also be found along the tributaries that form the Green River and the area around the Kentucky River. Carefully searching riverbeds, and exposed benches when water levels are low can be a good way to locate geodes throughout Kentucky.
Brachiopod was designated as Kentucky’s official state fossil. Brachiopods are fossilized shells of marine animals. Brachiopods are commonly found in the rock formations from the Paleozoic Era. The width of the brachiopod fossils is a little less than two inches on average.
Some other fossils such as bryozoans, corals, pelecypods, conodonts, gastropods, scolecodont teeth, cephalopods, monoplacophorans, crinoids and sponges can also be found in Kentucky in Jefferson, Carroll, Spencer, Nelson and Bullitt Counties.
The mineral fluorite have been found at locations in Kentucky such as the Columbia Mine in Crittenden County, East Faircloth Mine in Woodford County, Danville City in Boyle County, Huston Mine in Livingston County, Lafayette Mine in Crittenden County and Irvington in Breckinridge County.
There are a quite a few locations where quartz can be found in Kentucky. The Columbia Mine in Crittenden County, Halls Gap in Lincoln County, the Lafayette Mine in Crittenden County and at Kings Mountain in Lincoln County are all areas where quartz crystals have been found. Generally they are common clear crystals.