The January Mineralogy Study Group Meeting will be held via Zoom on Saturday, January 4th, 2025 at 7:30 PM. The topic is "Kentucky Agate". The presenter is Matthew Bentley, who is the Geologist for the State of Kentucky. Matthew attended Morehead State University and Western Kentucky University. He has been collecting Kentucky Agates for the past 10 years.
Kentucky Agate is the state rock and mineral of Kentucky. If you are not familiar with it, a good resource with information and pictures is: https://www.uky.edu/KGS/rocksmineral/state-agate.php
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).