Kentucky Rocks and Minerals

Kentucky may not have lots of rocks and minerals, but it has lots of fossils.

Long ago Kentucky was covered in shallow tropical seas, so brachiopod, coral, sponge, crinoid, trilobite, and nautiloid fossils are very common in stream beds and road cuts in the Bluegrass Region. In 1995, a single five-foot long amphibian fossil was found in sandstone, near the Western Kentucky Coal Field.

Like the neighboring Plains states, Kentucky is underlain by sedimentary rocks but is unglaciated and therefore more varied in character. Rugged eastern Kentucky belongs to the Allegheny plateau, a region of sharp ridges and deep valleys which includes extensive coalfields. The rest of the state is divided into the Mississippian plateaus and coalfields to the south and southwest and the blue-grass region of rolling hills to the north, all sloping gently to the Mississippi River. Kentucky has lots of natural resources, including coal, oil and gas, sand, clay, fluorspar, limestone, dolomite and gravel.

Swampy land and dead vegetation formed Kentucky's two main coal fields. Coal was discovered in Kentucky in 1750, and throughout the 1970s and 1980s, Kentucky led the U.S. in coal production. Coal was named Kentucky’s official state rock in 1998.

Kentucky contains both kimberlites in Elliott County and lamprophyre dikes in western Kentucky, which are common rocks that diamonds are found in, but both these areas have been explored extensively and no naturally occurring diamonds have ever been found in either of these rocks. A diamond was found in Adair County, but its source is unknown, there are no kimberlites or lamprophyres in the area and glaciers did not extend that far into Kentucky.

In 1986, the freshwater pearl was named the state’s official gemstone. Freshwater pearls are found in Kentucky in the Mississippi River Valley and the Tennessee River Valley. But damming of these rivers, over-harvesting, and increased pollution has severely depleted the population of natural pearl-producing mussels in these rivers.

Kentucky designated the Kentucky Agate as the state rock in 2000. Beautiful specimens of red, black, yellow, and gray banded agate have been discovered in Estill, Jackson, Powell, Madison, and Rockcastle Counties. Though a lot of the agate beds are on private property, sometimes Kentucky Agates can be found in gravel beds and near streams and rivers.

The Green River has long been renowned for its geode bounty. This area has yielded some truly impressive specimens, with sizes reaching up to two feet in diameter! The Warsaw Formation, in central Kentucky, produces geodes. And geodes can also be found on the shores of Lake Cumberland and Dale Hollow Lake. As the water levels fluctuate, geodes nestled within the bedrock along the shorelines become exposed.

The Illinois-Kentucky Fluorspar district is world-famous for the enormous quantity of large crystalline purple and yellow fluorite. Kentucky is among the most abundant fluorite states in the U.S. You can still find fluorite in quarries and mine dumps in the area. The Ben E. Clement Mineral Museum displays many of the finest American fluorite specimens and it is my understanding that the museum also plans scheduled digs for fluorite and other kinds of minerals.

Before venturing out-do some research on where and what you can collect. Remember you must have permission to collect on private property.

See my page on Rockhounding Rules for general information on the rules of collecting rocks on various lands.