Kentucky Agate
Agate is a microscopically crystalline variety of the mineral quartz. In 2024, Governor Beshear signed House Bill 378 to have agate declared as the official State Gemstone.
Agate has delicate and varying shades of color arranged in layers. In the typical occurrence, the bands are irregular, curved, or in concentric patterns. Agate is used as an ornamental material or in semi-precious jewelry. The color banding is usually related to chemical impurities; for example, iron gives a red or orange color and manganese or calcium give black or blue colors.
For the past couple decades, beautiful specimens of red, black, yellow, and gray banded agate have been discovered in Estill, Jackson, Powell, Madison, and Rockcastle Counties. These Kentucky agates are derived from the Renfro-Borden Formation of Early Mississippian age and can be collected along some river drainages where the Borden is exposed to weathering. Many of these agates are displayed at local rock shows. More pictures of Kentucky agates can be seen in the Kentucky Agate section of this website and in the book, "Kentucky Agate: State Rock and Mineral Treasure of the Commonwealth" (McIntosh and Anderson, 2014).
This book contains hundreds of photographs and shows the many colors, shapes, and textures of agates. It is available from University of Kentucky Press (www.kentuckypress.com) or at many bookshops.
Microscopic photographs of Kentucky agates
